This is exim.info, produced by makeinfo version 4.2 from
../doc/spec.texinfo.


File: exim.info,  Node: Top,  Next: Introduction,  Prev: (dir),  Up: (dir)



The Exim Mail Transfer Agent
****************************

The specification of the Exim Mail Transfer Agent is converted
mechanically into Texinfo format from its original marked-up source.
Some typographic representations are changed, chapters and sections
cannot be numbered, and Texinfo lacks the ability to mark updated parts
of the specification with change bars.

Because the chapters and sections are unnumbered, cross references are
set to their names. This makes the English a bit odd, with phrases like
`see chapter "Retry configuration"' but it seemed very cumbersome to
change this to `see the chapter entitled "Retry configuration"' each
time.

Each chapter, section, and configuration option has been placed in a
separate Texinfo node. Texinfo doesn't allow commas, colons, or
apostrophes in node names, which is a rather nasty restriction. I have
arranged not to use colons or apostrophes in section titles, but cannot
bring myself to omit them from titles such as "The foo, bar and baz
commands". For the corresponding node names I have just used multiple
occurrences of "and", though it looks very ugly.

If a chapter or section continues after a list of configuration options
that is not in a new section, a new node is started, using the
chapter's or section's name plus `(continued)'. The `Up' operation from
a section or configuration option returns to the start of the current
chapter; the `Up' operation at a chapter start returns to the top of
the document; the `Up' in a list of configuration options within a
section returns to the top of that section.

A number of drivers have options with the same name, so they have been
disambiguated by adding the name of the driver to the option's name.
Thus, for example, the specification of the `prefix' option of the
`appendfile' transport is in a node called `prefix (appendfile)'.

* Menu:

* Introduction::
* Incorporated code::
* How Exim delivers mail::
* Building and installing Exim::
* The Exim command line::
* File and database lookups::
* The Exim configuration file::
* Regular expressions::
* String expansions::
* Embedded Perl::
* Main configuration::
* Driver specifications::
* Environment for running local transports::
* Generic options for transports::
* The appendfile transport::
* The autoreply transport::
* The lmtp transport::
* The pipe transport::
* The smtp transport::
* Generic options common to both directors and routers::
* Additional generic options for directors::
* Options common to the aliasfile and forwardfile directors::
* The aliasfile director::
* The forwardfile director::
* The localuser director::
* The smartuser director::
* Additional generic options for routers::
* The domainlist router::
* The ipliteral router::
* The iplookup router::
* The lookuphost router::
* The queryprogram router::
* Retry configuration::
* Address rewriting::
* SMTP authentication::
* The plaintext authenticator::
* The cram_md5 authenticator::
* Encrypted SMTP connections using TLS/SSL::
* Customizing error and warning messages::
* The default configuration file::
* Multiple user mailboxes::
* Using Exim to handle mailing lists::
* Virtual domains::
* Intermittently connected hosts::
* Verification of incoming mail::
* Other policy controls on incoming mail::
* System-wide message filtering::
* SMTP processing::
* Message processing::
* Automatic mail processing::
* Log files::
* Day-to-day management::
* Exim utilities::
* The Exim monitor::
* Security considerations::
* Format of spool files::
* Adding new drivers or lookup types::
* Concept Index::


File: exim.info,  Node: Introduction,  Next: Incorporated code,  Prev: Top,  Up: Top

Introduction
************

"If I have seen further it is by standing on the shoulders of giants."
							 (Isaac Newton)




Exim is a mail transfer agent (MTA) for Unix systems connected to the
Internet.  Configuration files currently exist for the following
operating systems: AIX, BSDI, Darwin (Mac OS X), DGUX, FreeBSD,
GNU/Hurd, GNU/Linux, HI-OSF (Hitachi), HP-UX, IRIX, MIPS RISCOS,
NetBSD, OpenBSD, QNX, SCO, SCO SVR4.2 (aka UNIX-SV), Solaris (aka
SunOS5), SunOS4, Tru64-Unix (formerly Digital UNIX, formerly DEC-OSF1),
Ultrix, and Unixware. However, code is not available for determining
system load averages under Ultrix.

The terms and conditions for the use and distribution of Exim are
contained in the file `NOTICE'. Exim is distributed under the terms of
the GNU General Public Licence, a copy of which may be found in the
file `LICENCE'.

The use, supply or promotion of Exim for the purpose of sending bulk,
unsolicited electronic mail is incompatible with the basic aims of the
program, which revolve around the free provision of a service that
enhances the quality of personal communications. The author of Exim
regards indiscriminate mass-mailing as an antisocial, irresponsible
abuse of the Internet.

Exim owes a great deal to Smail 3 and its author, Ron Karr. Without the
experience of running and working on the Smail 3 code, I could never
have contemplated starting to write a new mailer. Many of the ideas and
user interfaces were originally taken from Smail 3, though the actual
code of Exim is entirely new, and has developed far beyond the initial
concept.

Many people, both in Cambridge and around the world, have contributed
to the development and the testing of Exim, and to porting it to
various operating systems. I am grateful to them all.

This document is very much a reference manual; it is not a tutorial.
Although there are some discussions and examples in places, the
information is mostly organized in a way that makes it easy to look up,
rather than in a natural order for sequential reading. Furthermore, the
manual aims to cover every aspect of Exim in detail, including a number
of rarely-used, special-purpose features that are unlikely to be of
very wide interest.

An `easier' discussion of Exim which provides more in-depth explanatory,
introductory, and tutorial material can be found in my book Exim The
Mail Transport Agent, published by O'Reilly (ISBN 0-596-00098-7).
Inevitably, however, the book is unlikely to be fully up-to-date with
the latest release.  This specification is the definitive reference.

This edition of the Exim specification applies to version 3.30 of Exim.
Substantive changes from the 3.20 edition are marked by bars in the
right-hand margin in the PostScript, PDF, and plain text versions of the
document. Changes are not marked in the Texinfo version, because Texinfo
doesn't support change bars. In the HTML version, a different colour is
used.  Minor corrections and rewordings are not marked.

As the program is still developing, there may be features in later
versions of the program that have not yet made it into this document,
which is updated only when the most significant digit of the fractional
part of the version number changes. However, all changes are noted
briefly in the file called `doc/ChangeLog', and specifications of new
features that are not yet in this manual are placed in `doc/NewStuff'.
Complete lists of options are maintained in `doc/OptionsLists.txt'.
All these files can be found within the Exim source distribution.



* Menu:

* Web site and Mailing list::
* Availability::
* Limitations::
* Features::
* Support for IPv6::
* Calling interface::
* Terminology::


File: exim.info,  Node: Web site and Mailing list,  Next: Availability,  Prev: Introduction,  Up: Introduction

Web site and Mailing list
=========================

There is a web site at http://www.exim.org by courtesy of Energis
Squared, formerly Planet Online Ltd, who are situated in the UK. The
site is mirrored in the USA and a number of of other countries; links
to the mirrors are listed on the home page.  Energis also provide
resources for the following mailing lists:

     exim-users@exim.org              general discussion list
     exim-announce@exim.org           moderated, low volume announcements list
     pop-imap@exim.org                discussion of POP/IMAP issues

You can subscribe to these lists, change your existing subscription,
and view or search the archives via the `mailing lists' link on the
Exim home page.

By courtesy of Martin Hamilton, there is also an archive of the
exim-users list in plain text form at
http://www.roads.lut.ac.uk/lists/exim-users/exim-users.archive and in
HTML via Hypermail at http://www.roads.lut.ac.uk/lists/exim-users/.
The list is also forwarded to http://www.egroups.com/list/exim-users,
which is another archiving system with searching capabilities.


File: exim.info,  Node: Availability,  Next: Limitations,  Prev: Web site and Mailing list,  Up: Introduction

Availability
============

The master ftp site for the Exim distribution is

     ftp://ftp.csx.cam.ac.uk/pub/software/email/exim

Those mirror sites that I know about are listed in the file

     ftp://ftp.csx.cam.ac.uk/pub/software/email/exim/Mirrors

The current release of Exim is always to be found in files called

     `exim-n.nn.tar.gz'
     and
     `exim-n.nn.tar.bz2'

where n.nn is the highest such version number in the directory.  The
two files contain identical data; the only difference is the type of
compression. The `.bz2' file is usually a lot smaller than the `.gz'
file.  When there is only a small amount of change from one version to
the next, a patch file may be provided, with a final component name of
the form

     `exim-patch-n.nn-m.mm.gz'

For each released version, the log of changes is made separately
available in the directory

     ftp://ftp.csx.cam.ac.uk/pub/software/email/exim/ChangeLogs

so that it is possible to find out what has changed without having to
download the entire distribution. The main distribution contains ASCII
versions of this specification and other documentation; other formats
of the documents are available in separate files:

     `exim-html-n.nn.tar.gz'
     `exim-pdf-n.nn.tar.gz'
     `exim-postscript-n.nn.tar.gz'
     `exim-texinfo-n.nn.tar.gz'

These tar files contain only the `/doc' directory, not the complete
distribution, and are also available in `.bz2' as well as `.gz' forms.

An FAQ is available in two different formats from

     ftp://ftp.csx.cam.ac.uk/pub/software/email/exim/FAQ.txt.gz
     ftp://ftp.csx.cam.ac.uk/pub/software/email/exim/FAQ.html.gz

The FAQ and other HTML documentation is also available online at the
web site and its mirrors.

At the ftp site, there is a directory called

     ftp://ftp.csx.cam.ac.uk/pub/software/email/exim/Contrib/

which contains miscellaneous files contributed to the Exim community by
Exim users, and there is also a collection of contributed configuration
examples in

     ftp://ftp.csx.cam.ac.uk/pub/software/email/exim/config.samples.tar.gz


File: exim.info,  Node: Limitations,  Next: Features,  Prev: Availability,  Up: Introduction

Limitations
===========

   * Exim is written in ANSI C. This should not be much of a limitation
     these days.  However, to help with systems that lack a true ANSI C
     library, Exim avoids making any use of the value returned by the
     "sprintf()" function, which is one of the main incompatibilities.
     It has its own version of "strerror()" for use with SunOS4 and any
     other system that lacks this function, and a macro can be defined
     to turn "memmove()" into "bcopy()" if necessary.  Exim uses file
     names that are longer than fourteen characters.

   * Exim is intended for use as an Internet mailer, and therefore
     handles addresses in RFC 822 domain format only.  It cannot handle
     `bang paths', though simple two-component bang paths can be
     converted by a straightforward rewriting configuration. This
     restriction does not prevent Exim from being interfaced to UUCP,
     provided domain addresses are used.

   * Exim insists that every address it handles has a domain attached.
     For incoming local messages, domainless addresses are
     automatically qualified with a configured domain value.
     Configuration options specify from which remote systems
     unqualified addresses are acceptable. These are then qualified on
     arrival.

   * The only external transport currently implemented is an SMTP
     transport over a TCP/IP network (using sockets, including support
     for IPv6). However, a pipe transport is available, and there are
     facilities for writing messages to files and pipes, optionally in
     "batched SMTP" format; these facilities can be used to send
     messages to some other transport mechanism such as UUCP, provided
     it can handle domain-style addresses. Batched SMTP input is also
     catered for.

   * Exim is not designed for storing mail for dial-in hosts. When the
     volumes of such mail are large, it is better to get the messages
     `delivered' into files (that is, off Exim's queue) and
     subsequently passed on to the dial-in hosts by other means.

   * It used not to be easy to set up Exim to rewrite addresses only in
     some copies of a message and not others, for example, to retain
     locally-meaningful addresses locally, but rewrite them for any
     copies of messages that are sent off-site. From release 3.20,
     doing this has been made a lot simpler by adding a facility for
     rewriting at transport time.


File: exim.info,  Node: Features,  Next: Support for IPv6,  Prev: Limitations,  Up: Introduction

Features
========

These are some of the main features of Exim:

   * Exim follows the same general approach of decentralized control
     that Smail does. There is no central process doing overall
     management of mail delivery.  However, unlike Smail, the
     independent delivery processes share data in the form of `hints',
     which makes delivery more efficient in some cases.  The hints are
     kept in a number of DBM files. If any of these files are lost, the
     only effect is to change the pattern of delivery attempts and
     retries.

   * Many configuration options can be given as expansion strings,
     which are transformed in various ways when they are used. As these
     can include file lookups, much of Exim's operation can be made
     table-driven if desired. For example, it is possible to do local
     delivery on a machine on which the users do not have accounts. The
     ultimate flexibility can be obtained (at a price) by running a
     Perl interpreter while expanding a string.

   * Exim has flexible retry algorithms, applicable to directing and
     routing addresses as well as to delivery.

   * Exim contains header and envelope rewriting facilities.

   * Unqualified addresses are accepted only from specified hosts or
     networks.

   * Exim can perform multiple deliveries down the same SMTP channel
     after deliveries have been delayed.

   * Exim can be configured to do local deliveries immediately but to
     leave remote (SMTP) deliveries until the message is picked up by a
     queue-runner process.  This increases the likelihood of multiple
     messages being sent down a single SMTP connection.

   * Remote deliveries of the same message to different hosts can
     optionally be done in parallel.

   * Incoming SMTP messages start delivery as soon as they are
     received, without waiting for the SMTP call to close.

   * Exim has support for the SMTP AUTH extension for authenticating
     clients, and for the STARTTLS extension for setting up encrypted
     connections.

   * Perl-compatible regular expressions are available in a number of
     configuration parameters.

   * Domain lists can include file lookups, making it possible to
     support very large numbers of local domains.

   * Exim supports optional checking of incoming return path (sender)
     and receiver addresses as they are received by SMTP.

   * SMTP calls from specific machines, optionally from specific
     idents, can be locked out, and incoming SMTP messages from
     specific senders can also be locked out. Exim also supports the
     use of the Realtime Blackhole List (RBL).

   * Hosts that are permitted to relay mail through a machine to
     another external domain can be controlled by IP number or IP
     network number. Relay control by recipient domain and sender
     address is also available.

   * Messages on the queue can be `frozen' and `thawed' by the
     administrator.

   * Exim can handle a number of independent local domains on the same
     machine; each domain can have its own alias files, etc. This
     facility is sometimes known as `virtual domains'.

   * Simple mailing lists can be handled directly by Exim itself (but
     for `serious' mailing list operations, it is best to use it in
     conjunction with specialist mailing list software).

   * Exim stats a user's home directory before looking for a `.forward'
     file, in order to detect the case of a missing NFS mount. Delivery
     is delayed if the directory is unavailable.

   * Exim contains an optional built-in mail filtering facility. This
     can be configured to allow users to provide personal filter files,
     and it is also possible for a system-wide filter file to be
     applied to every message.

   * There is support for multiple user mailboxes controlled by
     prefixes or suffixes on the user name, either via the filter
     mechanism or through multiple `.forward' files.

   * Periodic warnings are automatically sent to messages' senders when
     delivery is delayed - the time between warnings is configurable.
     The warnings can be made conditional on the contents of the
     message.

   * A queue run can be manually started to deliver just a particular
     portion of the queue, or those messages with a recipient whose
     address contains a given string.  There is support for the ETRN
     command in SMTP to interface to this.

   * Exim can be configured to run as root all the time, except when
     performing local deliveries, which it always does in a separate
     process under an appropriate uid and gid. Alternatively, it can be
     configured to run as root only when needed; in particular, it need
     not run as root when receiving incoming messages or when sending
     out messages over SMTP. See chapter "Security considerations" for
     a discussion of security issues.

   * I have tried to make the wording of delivery failure messages
     clearer and simpler, for the benefit of those less-experienced
     people who are now using email. Alternative wording for these
     messages can be provided in a separate file.

   * The Exim Monitor is an optional extra; it displays information
     about Exim's processing in an X window, and an administrator can
     perform a number of control actions from the window interface.
     However, all such actions are also available from the command line
     interface.


File: exim.info,  Node: Support for IPv6,  Next: Calling interface,  Prev: Features,  Up: Introduction

Support for IPv6
================

IPv6 is the next generation of IP protocol which will in time replace
IPv4; it is currently in an experimental state. A number of vendors
have already released IPv6 versions of their systems and networking
libraries.

If Exim is built with HAVE_IPV6 set, it uses the IPv6 API for TCP/IP
input and output. IP addresses can be given in IPv6 as well as IPv4
notation; incoming IPv4 calls use the embedded IPv6 address notation.
In the DNS, two new record types, A6 and AAAA, are used for finding
IPv6 addresses. A6 records are supposed, in time, to supersede AAAA
records. At present, to be on the safe side, when trying to find host
addresses from the DNS, Exim looks for all three record types: A6,
AAAA, and A, in that order, and builds a combined list of addresses
found (dropping any duplicates). In future this may change (for
example, to stop once one kind of address has been found).


File: exim.info,  Node: Calling interface,  Next: Terminology,  Prev: Support for IPv6,  Up: Introduction

Calling interface
=================

Like many MTAs, Exim has adopted the Sendmail interface so that it can
be a straight replacement for `/usr/lib/sendmail' or
`/usr/sbin/sendmail' when sending mail. Other compatible options also
exist, but those that produce output (for example, -bp, which lists the
messages on the queue) do so in Exim's own format.  All the relevant
Sendmail options are implemented, with two reservations. There are also
some additional options that are compatible with Smail 3, and some
further options that are new to Exim.

The -t option, for taking a list of recipients from a message's
headers, is documented (for several versions of Sendmail) as
suppressing delivery to any addresses on the command line (see `man'
pages on a number of operating systems). However, it appears that this
is not the case in practice. For this reason, Exim has an option called
"extract_addresses_remove_arguments" which controls its behaviour in
this regard.

Sendmail uses the -bi option as a request to rebuild the alias file. As
Exim does not have the concept of a single alias file, it cannot mimic
this behaviour. It can be configured to run a particular script when
this option is received; otherwise the option is ignored.

The run time configuration is held in a single text file which is
divided into a number of sections. The entries in this file consist of
keywords and values, in the style of Smail 3 configuration files. A
default configuration file which is suitable for simple installations
is provided in the distribution.

Control of messages on the queue can be done via certain privileged
command line options. There is also an optional monitor program called
"eximon", which displays current information in an X window, and
contains a menu interface to Exim's command line administration options.


File: exim.info,  Node: Terminology,  Prev: Calling interface,  Up: Introduction

Terminology
===========

The term "local part", which is taken from RFC 822, is used to refer to
that part of an email address that precedes the @ sign. The part that
follows the @ sign is called the "domain" or "mail domain".

The word "domain" is sometimes used to mean all but the first component
of a machine's name. It is not used in that sense here, where it
normally refers to the part of an email address following the @ sign.

"Local domains" are mail domains for which the current host is
responsible for handling the entire address; in other words, it has
special knowledge of what to do with messages sent to such domains, and
normally that means using the local part of the address either to
deliver the message on the local host or to transform the address using
an alias file or something similar. All other domains are "remote
domains", which normally cause the message to be transmitted to some
other host.

The distinction between local and remote domains is not always entirely
clear-cut, since a host can have special knowledge about routing for
remote domains, and messages for local domains may under some
circumstances be passed to other hosts.

The terms "local delivery" and "remote delivery" are used to distinguish
delivery to a file or a pipe on the local machine from delivery by SMTP
to some remote machine. The type of delivery does not necessarily
correspond to the type of address. Mail for a local domain may get
passed on to some other host, while mail for a remote domain might get
delivered locally to a file or pipe for onward transmission by some
other means. However, these are special cases.

The term "default" appears frequently in this manual. It is used to
qualify a value which is used in the absence of any setting in the
configuration. It may also qualify an action which is taken unless a
configuration setting specifies otherwise.

The term "defer" is used when the delivery of a message to a specific
destination cannot immediately take place for some reason (a remote
host may be down, or a user's local mailbox may be full). Such
deliveries are "deferred" until a later time.

The term "mailmaster" is used to refer to the person in charge of
maintaining the mail software on a given computer. Commonly this will
be the same person who fulfils the postmaster role, but this may not
always be the case.

The term "queue" is used to refer to the set of messages awaiting
delivery, because this term is in widespread use in the context of
MTAs. However, in Exim's case the reality is more like a pool than a
queue, because there is normally no ordering of waiting messages.

The term "queue-runner" is used to describe a process that scans the
queue and attempts to deliver those messages whose retry times have
come. This term is used by other MTAs, and also relates to the command
"runq", but in Exim the waiting messages are normally processed in an
unpredictable order.


File: exim.info,  Node: Incorporated code,  Next: How Exim delivers mail,  Prev: Introduction,  Up: Top

Incorporated code
*****************

A number of pieces of external code are included in the Exim
distribution.

   * Regular expressions are supported in the main Exim program and in
     the Exim monitor using the freely-distributable PCRE library,
     copyright (c) 2000 University of Cambridge. The source is
     distributed in the directory `src/pcre'.

   * RFC 1413 callbacks are supported in the main Exim program using
     the "libident" library made freely available by Peter Eriksson at
     ftp://ftp.lysator.liu.se.  Some modifications have been made in
     order to support IPv6. The source is distributed in the directory
     called `src/libident'.

   * Support for the cdb (Constant DataBase) lookup method is provided
     by code contributed by Nigel Metheringham of Planet Online Ltd.
     which contains the following statements:
     -------------------------------------------------------------------
     Copyright (c) 1998 Nigel Metheringham, Planet Online Ltd

     This program is free software; you can redistribute it and/or
     modify it under the terms of the GNU General Public License as
     published by the Free Software Foundation; either version 2 of the
     License, or (at your option) any later version.

     This code implements Dan Bernstein's Constant DataBase (cdb) spec.
     Information, the spec and sample code for cdb can be obtained from
     http://www.pobox.com/~djb/cdb.html. This implementation borrows
     some code from Dan Bernstein's implementation (which has no
     license restrictions applied to it).
     -------------------------------------------------------------------
     The implementation is completely contained within the code of Exim.
     It does not link against an external cdb library.

   * The Exim Monitor program, which is an X-Window application,
     includes modified versions of the Athena StripChart and TextPop
     widgets.  This code is copyright by DEC and MIT, and their
     permission notice appears below, in accordance with the conditions
     expressed therein.

------------------------------------------------------------------------
Copyright 1987, 1988 by Digital Equipment Corporation, Maynard,
Massachusetts, and the Massachusetts Institute of Technology,
Cambridge, Massachusetts.

                          All Rights Reserved

Permission to use, copy, modify, and distribute this software and its
documentation for any purpose and without fee is hereby granted,
provided that the above copyright notice appear in all copies and that
both that copyright notice and this permission notice appear in
supporting documentation, and that the names of Digital or MIT not be
used in advertising or publicity pertaining to distribution of the
software without specific, written prior permission.

DIGITAL DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING
ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO EVENT SHALL
DIGITAL BE LIABLE FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR
ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS,
WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION,
ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
SOFTWARE.
------------------------------------------------------------------------

File: exim.info,  Node: How Exim delivers mail,  Next: Building and installing Exim,  Prev: Incorporated code,  Up: Top

How Exim delivers mail
**********************



* Menu:

* Philosophy::
* Message reception::
* Life of a message::
* Drivers::
* Delivery in detail::
* Temporary delivery failures::


File: exim.info,  Node: Philosophy,  Next: Message reception,  Prev: How Exim delivers mail,  Up: How Exim delivers mail

Philosophy
==========

Exim is designed to work efficiently on systems that are permanently
connected to the Internet and are handling a general mix of mail. In
such circumstances, most messages can be delivered immediately.
Consequently, Exim does not maintain independent queues of messages for
specific domains or hosts, though it does try to send several messages
in a single SMTP connection after a host has been down, and it also
maintains per-host retry information.


File: exim.info,  Node: Message reception,  Next: Life of a message,  Prev: Philosophy,  Up: How Exim delivers mail

Message reception
=================

When Exim receives a message, it writes two files in its spool
directory. The first contains the "envelope" information, the current
status of the message, and the headers, while the second contains the
body of the message.

The envelope information consists of the address of the message's
sender and the address(es) of the recipient(s). This information is
entirely separate from any addresses contained in the headers. The
status of the message includes a list of recipients who have already
received the message. The format of the first spool file is described
in chapter "Format of spool files".

Address rewriting that is specified in the rewrite section of the
configuration (see chapter "Address rewriting") is done once and for
all on incoming addresses, both in the header and the envelope, at the
time the message is received. If during the course of delivery
additional addresses are generated (for example, via aliasing), these
new addresses get rewritten as soon as they are generated.  At the time
a message is actually delivered (transported) further rewriting can
take place; because this is a transport option, it can be different for
different forms of delivery. It is also possible to specify the
addition or removal of certain headers at the time the message is
delivered (see chapters "Generic options for transports" and "Generic
options common to both directors and routers").

Every message handled by Exim is given a "message id" which is sixteen
characters long. It is divided into three parts, separated by hyphens.
Each part is a sequence of letters and digits, representing a number in
base 62:

   * The first six characters are the time the message was received, as
     a number in seconds - the normal Unix way of representing a time
     of day.  If the clock goes backwards (due to resetting) in a
     process that is receiving more than one message, the later time is
     retained.

   * After the first hyphen, the next six characters are the id of the
     process that received the message.

   * The final two characters, after the second hyphen, are used to
     ensure uniqueness of the id. There are two different formats:

       1. If the "localhost_number" option is not set, uniqueness is
          required only within the local host. This portion of the id
          is `00' except when a process receives more than one message
          in a single second, when the number is incremented for each
          additional message.

       2. If the "localhost_number" option is set, uniqueness among a
          set of hosts is required. This portion of the id is set to
          the base 62 encoding of

               <sequence number> * 256 + <host number>

          where <sequence number> is the count of messages received by
          the current process within the current second. As the maximum
          value of the host number is 255, this allows for a maximum
          value of 14 for the sequence number. If this limit is
          reached, a delay of one second is imposed before reading the
          next message, in order to allow the clock to tick and the
          sequence number to get reset.


The names of the two spool files consist of the message id, followed by
-H for the file containing the envelope and headers, and -D for the data
file.

By default all these spool files are held in a single directory called
`input' inside the general Exim spool directory. Some operating systems
do not perform very well if the number of files in a directory gets
very large; to improve performance in such cases, the
"split_spool_directory" option can be used. This causes Exim to split
up the input files into 62 sub-directories whose names are single
letters or digits.

Exim can be configured not to start a delivery process when a message is
received; this can be unconditional, or depend on the number of
incoming SMTP connections or the system load. In these situations, new
messages wait on the queue until a queue-runner process picks them up.
However, in standard configurations under normal conditions, delivery
is started as soon as a message is received.


File: exim.info,  Node: Life of a message,  Next: Drivers,  Prev: Message reception,  Up: How Exim delivers mail

Life of a message
=================

A message remains in the spool directory until it is completely
delivered to its recipients or to an error address, or until it is
deleted by an administrator or by the user who originally created it.
In cases when delivery cannot proceed - for example, when a message can
neither be delivered to its recipients nor returned to its sender, the
message is marked `frozen' on the spool, and no more deliveries are
attempted.

An administrator can `thaw' such messages when the problem has been
corrected, and can also freeze individual messages by hand if
necessary. In addition, an administrator can force a delivery error,
causing an error message to be sent.

There is also an "auto_thaw" option, which can be used to cause Exim to
retry frozen messages after a certain time. When this is set, no
message will remain on the queue for ever, because the delivery timeout
will eventually be reached.  Delivery failure reports that reach this
timeout are discarded.

When an Exim process starts to deliver a message, it takes out a lock
on the -D file, to prevent any other Exim process from working on it.
As delivery proceeds, Exim writes timestamped information about each
address to a per-message log file; this includes any delivery error
messages. This log is solely for the benefit of the administrator, and
is normally deleted with the spool files when processing of a message
is complete. However, Exim can be configured to retain it (a dangerous
option, as the files can accumulate rapidly on a busy system). Exim
also writes delivery messages to its main log file, whose contents are
described in chapter "Log files".

All the information Exim itself needs to set up a delivery is kept in
the first spool file with the headers. When a successful delivery
occurs, the address is immediately written at the end of a journal
file, whose name is the message id followed by -J. At the end of a
delivery run, if there are some addresses left to be tried again later,
the first spool file (the -H file) is updated to indicate which these
are, and the journal file is then deleted.  Updating the spool file is
done by writing a new file and renaming it, to minimize the possibility
of data loss.

Should the system or the program crash after a successful delivery but
before the spool file has been updated, the journal is left lying
around. The next time Exim attempts to deliver the message, it reads
the journal file and updates the spool file before proceeding. This
minimizes the chances of double deliveries caused by crashes.


File: exim.info,  Node: Drivers,  Next: Delivery in detail,  Prev: Life of a message,  Up: How Exim delivers mail

Drivers
=======

The main delivery processing elements of Exim are called directors,
routers, and transports, and collectively these are known as drivers.
Code for a number of them is provided, compile-time options specify
which ones are included in the binary, and run time options specify
which ones are actually used.

A transport is a driver that transmits a copy of the message from Exim's
spool to some destination. There are two kinds of transport: for a local
transport, the destination is a file or a pipe on the local host,
whereas for a remote transport the destination is some other host. A
message is passed to a specific transport as a result of successful
directing or routing. If a message has several recipients, it may be
passed to a number of different transports.

A director is a driver that operates on a local address, either
determining how its delivery should happen, or converting the address
into one or more new addresses (for example, via an alias file). A
local address is one whose domain matches an entry in the list given in
the "local_domains" option, or has been determined to be local by a
router - see below. The fact that an address is local does not imply
that the message has to be delivered locally; it can be directed either
to a local or to a remote transport.

A router is a driver that operates on an apparently remote address, that
is an address whose domain does not match anything in the list given in
"local_domains". When a router succeeds it can route an address either
to a local or to a remote transport, or it can change the domain, and
pass the address on to subsequent routers.

In exceptional cases, a router may determine that an address is local
after all, and cause it to be passed to the directors. This happens
automatically if a host lookup expands an abbreviated domain into one
that is local. It can also be made to happen (optionally) if an MX
record or other routing information points to the local host, though by
default this situation is treated as a configuration error.  This is
the only case in which the directors are used to process an address
that may not match anything in "local_domains". The diagram below
illustrates the relationship between the three kinds of driver.

                              address
                                 |
                                 |<---------- new address --------
                                 V                               |
                         -----------------                       |
                         |    matches    |                       |
          ------- no ----| local_domains |--- yes -------        |
          |              |    option?    |              |        |
          V              -----------------              V        |
     -----------                                   ------------  |
     | routers |--- local after all ------------->| directors |---
     -----------                                  -------------
          |                -------------                |
          ---------------->| transport |<----------------
                           |  queues   |
                           -------------

As new features have been added to Exim, the distinction between
routers and directors has become less clear-cut than it once was.  It
is possible that in some future release the difference will be
abolished and they will be merged into one type of driver. However, at
present, they remain distinct.


File: exim.info,  Node: Delivery in detail,  Next: Temporary delivery failures,  Prev: Drivers,  Up: How Exim delivers mail

Delivery in detail
==================

When a message is to be delivered, the sequence of events is roughly as
follows:

   * If a system-wide filter file is specified, the message is passed
     to it. The filter may add recipients to the message, replace the
     recipients, discard the message, cause a new message to be
     generated, or cause the message delivery to fail. The format of
     the filter file is the same as for user filter files, described in
     the separate document entitled "Exim's interface to mail
     filtering". Some additional features are available in system
     filters - see chapter "System-wide message filtering" for details.
     Note that a message is passed to the system filter only once per
     delivery attempt, however many recipients it has.  However, if
     there are several delivery attempts because one or more addresses
     could not be immediately delivered, the system filter is run each
     time. The filter condition "first_delivery" can be used to detect
     this.

   * Each recipient address is parsed and a check is made to see if it
     is local, by comparing the domain with the list in the
     "local_domains" option. This can contain wildcards and file
     lookups.

   * If an address is local, it is offered to each configured director
     in turn until one is able to handle it.  When a director cannot
     handle an address, it is said to "decline". If no directors can
     handle the address, that is, if they all decline, the address is
     failed. Directors can be targeted at particular local domains, so
     several local domains can be processed entirely independently of
     each other.

   * A director that accepts an address may set up a local or a remote
     transport for it. The transport is not run at this time; the
     address is placed on a queue for the particular transport, to be
     run later. Alternatively, the director may generate one or more
     new addresses (typically from alias, forward, or filter files).
     New addresses are fed back into this process from the top, but in
     order to avoid loops, a director ignores any address which has an
     identically-named ancestor that was processed by itself.

   * If an address is not local, it is offered to each configured
     router in turn, until one is able to handle it. If none can, the
     address is failed.

   * A router that accepts an address may set up a transport for it, or
     may pass an altered address to subsequent routers, or it may
     discover that the address is a local address after all. This
     typically happens when a partial domain name is used and (for
     example) the DNS lookup is configured to try to extend such names.
     In this case, the address is passed to the directors. Exim can
     also be configured to do this for any domain whose lowest MX
     record or other routing information points to the local host.

   * Routers normally set up remote transports for messages that are to
     be delivered to other machines. However, a router can pass a
     message to a local transport, and by this means such messages can
     be routed to transport mechanisms other than SMTP by means of
     pipes or files.

   * When all the directing and routing is done, addresses that have
     been successfully handled are passed to their assigned transports.
     When local transports are doing real local deliveries, they handle
     only one address at a time, but if a local transport is being used
     as a pseudo-remote transport (for example, to collect batched SMTP
     messages for transmission by some other means) multiple addresses
     can be handled. Remote transports can always handle more than one
     address at once, but can be configured not to do so, or to restrict
     multiple addresses to the same domain.

   * Each local delivery runs in a separate process under a
     non-privileged uid, and they are run in sequence. Exim can be
     configured so that remote deliveries run under a uid that is
     private to Exim, instead of running as root. By default the remote
     deliveries run one at a time in the main Exim process, but a
     configuration option is available to allow multiple remote
     deliveries for a single message to be run simultaneously, each in
     its own sub-process.

   * When it is doing a queue run, Exim checks its retry database to
     see if there has been a previous temporary delivery failure for
     the address before running any local transport. If it finds one,
     it does not attempt a new delivery until the retry time for the
     address is reached. However, this happens only for delivery
     attempts that are part of a queue run. Local deliveries are always
     attempted when delivery immediately follows message reception.

   * Remote transports do their own retry handling, since an address
     may be deliverable to one of a number of hosts, each of which may
     have a different retry time. If there have been previous temporary
     failures and no host has reached its retry time, no delivery is
     attempted, whether in a queue run or not. See chapter "Retry
     configuration" for details of retry strategies.

   * If there were any errors, a message is returned to an appropriate
     address (the sender in the common case), with details of the error
     for each failing address.  Exim can be configured to send copies
     of error messages to other addresses.

   * If one or more addresses suffered a temporary failure, the message
     is left on the queue, to be tried again later. Otherwise the spool
     files and message log are deleted, though the message log can
     optionally be preserved if required.

Delivery is said to be "deferred" when the message remains on the queue
for a subsequent delivery attempt after a temporary failure. Such
messages get processed again by queue-runner processes that are
periodically started, either by an Exim daemon or via "cron" or by hand.

Temporary failures may be detected during routing and directing as well
as during the transport stage. Exim uses a set of configured rules to
determine when next to retry the failing address (see chapter "Retry
configuration").  These rules also specify when Exim should give up
trying to deliver to the address, at which point it generates a failure
report.

When a delivery is not part of a queue run (typically an immediate
delivery on receipt of a message), the directors are always run for
local addresses, and local deliveries are always attempted, even if
retry times are set for them.  This makes for better behaviour if one
particular message is causing problems (for example, causing quota
overflow, or provoking an error in a filter file).  If such a delivery
suffers a temporary failure, the retry data gets updated as usual, for
use by the next queue-runner process.

When a message cannot be delivered to some or all of its intended
recipients, a delivery failure report is generated. All the addresses
that failed in a given delivery attempt are listed in a single failure
report. If a message has many recipients, it is possible for some
addresses to fail in one delivery attempt and others to fail
subsequently, giving rise to more than one failure report for a single
message. The wording of delivery failure reports can be customized by
the administrator. See chapter "Customizing error and warning messages"
for details.

Delivery failure messages contain an "X-Failed-Recipients:" header,
listing all failed addresses, for the benefit of programs that try to
analyse such messages automatically.

A failure report is normally sent to the sender of the original
message, as obtained from the message's envelope. For incoming SMTP
messages, this is the address given in the MAIL command. However, when
an address is expanded via a forward or alias file, an alternative
address can be specified for delivery failures of the generated
addresses. For a mailing list expansion (see chapter "Using Exim to
handle mailing lists") it is common to direct failure reports to the
manager of the list.

If a failure report (either locally generated or received from a remote
host) itself suffers a delivery failure, the message is left on the
queue, but is `frozen', awaiting the attention of an administrator.
There are options which can be used to make Exim discard such failure
reports, or to keep them for only a short time.


File: exim.info,  Node: Temporary delivery failures,  Prev: Delivery in detail,  Up: How Exim delivers mail

Temporary delivery failures
===========================

There are many reasons why a message may not be immediately deliverable
to a particular address. Failure to connect to a remote machine
(because it, or the connection to it, is down) is one of the most
common. Local deliveries may also be delayed if NFS files are
unavailable, or if a mailbox is on a file system where the user is over
quota. Exim can be configured to impose its own quotas on local
mailboxes; where system quotas are set they will also apply.

A machine that is connected to the Internet can normally deliver most
mail straight away (the usual figure at Cambridge University is 98%).
In its default configuration, Exim starts a delivery process whenever
it receives a message, and usually this completes the entire delivery.
This is a lightweight approach, avoiding the need for any centralized
queue managing software. There are those who argue that a central
message manager would be able to batch up messages for the same host
and send them in a single SMTP call. I do not myself believe this would
occur much in general, unless messages were significantly delayed in
order to create a batch.

However, if a host is unreachable for a period of time, a number of
messages may be waiting for it by the time it recovers, and sending
them in a single SMTP connection is clearly beneficial. Whenever a
delivery to a remote host is deferred, Exim makes a note in its hints
database, and whenever a successful SMTP delivery has happened, it
looks to see if any other messages are waiting for the same host. If
any are found, they are sent over the same SMTP connection, subject to
a configuration limit as to the maximum number in any one connection.


File: exim.info,  Node: Building and installing Exim,  Next: The Exim command line,  Prev: How Exim delivers mail,  Up: Top

Building and installing Exim
****************************



* Menu:

* Unpacking::
* Multiple machine architectures and operating systems::
* DBM libraries::
* Pre-building configuration::
* Including TLS/SSL encryption support::
* Use of tcpwrappers::
* Including support for IPv6::
* The building process::
* Overriding build-time options for Exim::
* OS-specific header files::
* Overriding build-time options for the monitor::
* Installing commands and scripts::
* Installing info documentation::
* Setting up the spool directory::
* Testing::
* Switching Exim on::
* Exim on heavily loaded hosts::
* Stopping Exim on Solaris::


File: exim.info,  Node: Unpacking,  Next: Multiple machine architectures and operating systems,  Prev: Building and installing Exim,  Up: Building and installing Exim

Unpacking
=========

Exim is distributed as a gzipped or bzipped tar file which, when
upacked, creates a directory with the name of the current release (for
example, `exim-3.30') into which the following files are placed:

     `CHANGES'        contains a reference to where changes are documented
     `LICENCE'        the GNU General Public Licence
     `Makefile'       top-level make file
     `NOTICE'         conditions for the use of Exim
     `README'         list of files, directories and simple build instructions

Other files whose names begin with `README' may also be present. The
following subdirectories are created:

     `OS'             OS-specific files
     `doc'            documentation files
     `exim_monitor'   source files for the Exim monitor
     `scripts'        scripts used in the build process
     `src'            remaining source files
     `util'           independent utilities

Some utilities are contained in the `src' directory, and are built with
the Exim binary; those distributed in the `util' directory are things
like the log file analyser, which do not depend on any compile-time
configuration.


File: exim.info,  Node: Multiple machine architectures and operating systems,  Next: DBM libraries,  Prev: Unpacking,  Up: Building and installing Exim

Multiple machine architectures and operating systems
====================================================

The building process for Exim is arranged to make it easy to build
binaries for a number of different architectures and operating systems
from the same set of source files. Compilation does not take place in
the `src' directory. Instead, a "build directory" is created for each
architecture and operating system.  Symbolic links to the sources are
installed in this directory, which is where the actual building takes
place.

In most cases, Exim can discover the machine architecture and operating
system for itself, but the defaults can be overridden if necessary.


File: exim.info,  Node: DBM libraries,  Next: Pre-building configuration,  Prev: Multiple machine architectures and operating systems,  Up: Building and installing Exim

DBM libraries
=============

Licensed versions of Unix normally contain a library of DBM functions
operating via the `ndbm' interface, and this is what Exim expects by
default. Free versions of Unix seem to vary in what they contain as
standard. In particular, some versions of Linux have no default DBM
library, and different distributors have chosen to bundle different
libraries with their packaged versions.  However, the more recent
releases seem to have standardised on the Berkeley DB library.

Different DBM libraries have different conventions for naming the files
they use. When a program opens a file called `dbmfile', there are four
possibilities:

  1. A traditional ndbm implementation, such as that supplied as part
     of Solaris 2, operates on two files called `dbmfile.dir' and
     `dbmfile.pag'.

  2. The GNU library, "gdbm", operates on a single file, but makes two
     different hard links to it with names `dbmfile.dir' and
     `dbmfile.pag'.

  3. The Berkeley DB package, if called via its ndbm compatibility
     interface, operates on a single file called `dbmfile.db', but
     otherwise looks to the programmer exactly the same as the
     traditional ndbm implementation.

  4. If the Berkeley package is used in its native mode, it operates on
     a single file called `dbmfile'; the programmer's interface is
     somewhat different to the traditional ndbm interface.

  5. Yet another DBM library, called tdb, has become available from

          http://download.sourceforge.net/tdb

     It has its own interface, and also operates on a single file.

Exim and its utilities can be compiled to use any of these interfaces.
By default it assumes an interface of type (1), though some operating
system configuration files default to assuming (4). In order to use the
Berkeley DB package in native mode, it is necessary to set USE_DB in an
appropriate configuration file, and to use tdb you must set USE_TDB. It
may also be necessary to set DBMLIB, as in one of these lines:

     DBMLIB = -ldb
     DBMLIB = -ltdb

To complicate things further, there are now three very different
versions of the Berkeley DB package. Version 1.85 has been stable for
quite some time, releases 2.x were current for a while, but the latest
versions are numbered 3.x. Releases 2 and 3 are very different
internally and externally from the 1.85 release. All versions of
Berkeley DB can be obtained from

     http://www.sleepycat.com/

but maintenance of version 1.85 has been phased out, and it may not
compile on some systems. Maintenance for the 2.x releases will cease
shortly. There is further discussion about the various DBM libraries in
the file `doc/dbm.discuss.txt'.


File: exim.info,  Node: Pre-building configuration,  Next: Including TLS/SSL encryption support,  Prev: DBM libraries,  Up: Building and installing Exim

Pre-building configuration
==========================

Before building Exim, a local configuration file that specifies options
independent of any operating system has to be created with the name
`Local/Makefile'. A template for this file is supplied as the file
`src/EDITME', and it contains full descriptions of all the option
settings therein.  If you are building Exim for the first time, the
simplest thing to do is to copy `src/EDITME' to `Local/Makefile', then
read it and edit it appropriately.

Default values are supplied for everything except the settings that
specify the locations of the run time configuration file and the
directory for holding Exim binaries. These must be given, as Exim will
not build without them.  There are a few parameters that can be
specified either at build time or at run time to enable the same binary
to be used on a number of different machines.  However, if the
locations of Exim's spool directory and log file directory (if not
within the spool directory) are fixed, it is recommended that you
specify them in `Local/Makefile' instead of at run time so that errors
detected early in Exim's execution (such as a malformed configuration
file) can be logged.

If you are going to build the Exim monitor, a similar configuration
process is required. The file `exim_monitor/EDITME' must be edited
appropriately for your installation and saved under the name
`Local/eximon.conf'. If you are happy with the default settings
described in `exim_monitor/EDITME', `Local/eximon.conf' can be empty,
but it must exist.

This is all the configuration that is needed in straightforward cases
for known operating systems. However, the building process is set up so
that it is easy to override options that are set by default or by
operating-system-specific configuration files, for example to change
the name of the C compiler, which defaults to "gcc". See section
"Overriding build-time options for Exim" below for details of how to do
this.


File: exim.info,  Node: Including TLS/SSL encryption support,  Next: Use of tcpwrappers,  Prev: Pre-building configuration,  Up: Building and installing Exim

Including TLS/SSL encryption support
====================================

Exim can be built to support encrypted SMTP connections, using the
STARTTLS command (RFC 2487). Before you can do this, you must install
the OpenSSL library, which Exim uses for this purpose. There is no
cryptographic code in Exim itself. Once OpenSSL is installed, you can
set

     SUPPORT_TLS = yes
     TLS_LIBS=-lssl -lcrypto

in `Local/Makefile'. You may also need to specify the locations of the
OpenSSL library and include files. For example:

     SUPPORT_TLS = yes
     TLS_LIBS=-L/usr/local/openssl/lib -lssl -lcrypto
     TLS_INCLUDE=-I/usr/local/openssl/include/

You don't need to set TLS_INCLUDE if the relevant directory is already
specified in INCLUDE.


File: exim.info,  Node: Use of tcpwrappers,  Next: Including support for IPv6,  Prev: Including TLS/SSL encryption support,  Up: Building and installing Exim

Use of tcpwrappers
==================

Exim can be linked with the "tcpwrappers" library in order to check
incoming SMTP calls using the "tcpwrappers" control files. This may be
a convenient alternative to Exim's own checking facilities for
installations that are already making use of "tcpwrappers" for other
purposes. To do this, you should set USE_TCP_WRAPPERS in
`Local/Makefile', arrange for the file `tcpd.h' to be available at
compile time, and also ensure that the library `libwrap.a' is available
at link time, typically by including -lwrap in EXTRALIBS_EXIM.  For
example, if "tcpwrappers" is installed in `/usr/local', you might have

     USE_TCP_WRAPPERS=yes
     CFLAGS=-O -I/usr/local/include
     EXTRALIBS_EXIM=-L/usr/local/lib -lwrap

in `Local/Makefile'. The name to use in the "tcpwrappers" control files
is `exim'. For example, the line

     exim : LOCAL  192.168.0.  .friendly.domain

in your `/etc/hosts.allow' file allows connections from the local host,
from the subnet 192.168.0.0/24, and from all hosts in
"friendly.domain". All other connections are denied. Consult the
"tcpwrappers" documentation for further details.


File: exim.info,  Node: Including support for IPv6,  Next: The building process,  Prev: Use of tcpwrappers,  Up: Building and installing Exim

Including support for IPv6
==========================

Exim contains code for use on systems that have IPv6 support. Setting
HAVE_IPV6=YES in `Local/Makefile' causes the IPv6 code to be included;
it may also be necessary to set IPV6_INCLUDE and IPV6_LIBS on systems
where the IPv6 support is not fully integrated into the normal include
and library files.


File: exim.info,  Node: The building process,  Next: Overriding build-time options for Exim,  Prev: Including support for IPv6,  Up: Building and installing Exim

The building process
====================

Once `Local/Makefile' (and `Local/eximon.conf', if required) have been
created, run "make" at the top level. It determines the architecture and
operating system types, and creates a build directory if one does not
exist.  For example, on a Sun system running Solaris 2.5.1, the
directory `build-SunOS5-5.5.1-sparc' is created.  Symbolic links to
relevant source files are installed in the build directory.

If this is the first time "make" has been run, it calls a script which
builds a make file inside the build directory, using the configuration
files from the `Local' directory. The new make file is then passed to
another instance of "make" which does the real work, building a number
of utility scripts, and then compiling and linking the binaries for the
Exim monitor (if configured), a number of utilities, and finally Exim
itself. The command "make makefile" can be used to force a rebuild of
the make file in the build directory, should this ever be necessary.

If you have problems building Exim, check for any comments there may be
in the `README' file concerning your operating system, and also take a
look at the FAQ, where some common problems are covered.


File: exim.info,  Node: Overriding build-time options for Exim,  Next: OS-specific header files,  Prev: The building process,  Up: Building and installing Exim

Overriding build-time options for Exim
======================================

The main make file that is created at the beginning of the building
process consists of the concatenation of a number of files which set
configuration values, followed by a fixed set of "make" instructions.
If a value is set more than once, the last setting overrides any
previous ones. This provides a convenient way of overriding defaults.
The files that are concatenated are, in order:

     OS/Makefile-Default
     OS/Makefile-<ostype>
     Local/Makefile
     Local/Makefile-<ostype>
     Local/Makefile-<archtype>
     Local/Makefile-<ostype>-<archtype>
     OS/Makefile-Base

where <ostype> is the operating system type and <archtype> is the
architecture type. `Local/Makefile' is required to exist, and the
building process fails if it is absent. The other three `Local' files
are optional, and are often not needed.

The values used for <ostype> and <archtype> are obtained from scripts
called `scripts/os-type' and `scripts/arch-type' respectively. If
either of the environment variables EXIM_OSTYPE or EXIM_ARCHTYPE is
set, their values are used, thereby providing a means of forcing
particular settings.  Otherwise, the scripts try to get values from the
"uname" command. If this fails, the shell variables OSTYPE and ARCHTYPE
are inspected. A number of ad hoc transformations are then applied, to
produce the standard names that Exim expects. You can run these scripts
directly from the shell in order to find out what values are being used
on your system.

`OS/Makefile-Default' contains comments about the variables that are set
therein. Some (but not all) are mentioned below. If there is something
that needs changing, review the contents of this file and the contents
of the make file for your operating system (`OS/Makefile-<ostype>') to
see what the default values are.

If you need to change any of the values that are set in
`OS/Makefile-Default' or in `OS/Makefile-<ostype>', or to add any new
definitions, do so by putting the new values in an appropriate `Local'
file.  For example, to specify that the C compiler is called "cc"
rather than "gcc" when compiling in the OSF1 operating system, and that
it is to be to be called with the flag -std1, create a file called
`Local/Makefile-OSF1' containing the lines

     CC=cc
     CFLAGS=-std1

This makes it easy to transfer your configuration settings to new
versions of Exim simply by copying the contents of the `Local'
directory.

Exim contains support for doing LDAP, NIS, NIS+, and other kinds of file
lookup, but not all systems have these components installed, so the
default is not to include the relevant code in the binary. All the
different kinds of file and database lookup that Exim supports are
implemented as separate code modules which are included only if the
relevant compile-time options are set. In the case of LDAP, NIS, and
NIS+, the settings for `Local/Makefile' are:

     LOOKUP_LDAP=yes
     LOOKUP_NIS=yes
     LOOKUP_NISPLUS=yes

and similar settings apply to the other lookup types. In most cases the
relevant include files and interface libraries need to be installed
before compiling Exim.  However, in the case of cdb, which is included
in the binary only if

     LOOKUP_CDB=yes

is set, the code is entirely contained within Exim, and no external
include files or libraries are required.

When a lookup type is not included in the binary, attempts to configure
Exim to use it cause configuration errors.

Exim can be linked with an embedded Perl interpreter, allowing Perl
subroutines to be called during string expansion. To enable this
facility,

     EXIM_PERL=perl.o

must be defined in `Local/Makefile'. Details of this facility are given
in chapter "Embedded Perl".

The location of the X11 libraries is something that varies a lot between
operating systems, and of course there are different versions of X11 to
cope with. The following three variables are set in
`OS/Makefile-Default':

     X11=/usr/X11R5
     XINCLUDE=-I$(X11)/include
     XLFLAGS=-L$(X11)/lib

These are overridden in some of the operating-system configuration
files. For example, in `OS/Makefile-SunOS5' there is

     X11=/usr/openwin
     XINCLUDE=-I$(X11)/include
     XLFLAGS=-L$(X11)/lib -R$(X11)/lib

If you need to override the default setting for your operating system,
place a definition of all three of these variables into your
`Local/Makefile-<ostype>' file.

If you need to add any extra libraries to the link steps, these can be
put in a variable called EXTRALIBS, which appears in all the link
commands, but by default is not defined.  In contrast, EXTRALIBS_EXIM
is used only on the command for linking the main Exim binary, and not
for any associated utilities.  There is also DBMLIB, which appears in
the link commands for binaries that use DBM functions (see also section
"DBM libraries"). Finally, there is EXTRALIBS_EXIMON, which appears
only in the link step for the Exim monitor binary, and which can be
used, for example, to include additional X11 libraries.

Another variable which is not normally defined is STDERR_FILE. This
defines a file to which debugging output is written if the -df flag is
set, and is of use when running Exim under "inetd".

Yet another variable which should not normally be needed is ERRNO_QUOTA.
Exim needs to know which error the operating system gives when writing
to a file fails because the user is over quota. POSIX specifies an
error called EDQUOT and this is present in the latest versions of all
the systems Exim has been ported to at the time of writing. However, it
is not present in earlier versions of SunOS5, which use ENOSPC instead.
The code of Exim defaults to using EDQUOT if it is defined, and ENOSPC
otherwise. You should set ERRNO_QUOTA only if your system uses some
completely different error code.

The make file copes with rebuilding Exim correctly if any of the
configuration files are edited. However, if an optional configuration
file is deleted, it is necessary to touch the associated non-optional
file (that is, `Local/Makefile' or `Local/eximon.conf') before
rebuilding.


File: exim.info,  Node: OS-specific header files,  Next: Overriding build-time options for the monitor,  Prev: Overriding build-time options for Exim,  Up: Building and installing Exim

OS-specific header files
========================

The `OS' directory contains a number of files with names of the form
`os.h-<ostype>'. These are system-specific C header files that should
not normally need to be changed. There is a list of macro settings that
are recognized in the file `OS/os.configuring', which should be
consulted if you are porting Exim to a new operating system.


File: exim.info,  Node: Overriding build-time options for the monitor,  Next: Installing commands and scripts,  Prev: OS-specific header files,  Up: Building and installing Exim

Overriding build-time options for the monitor
=============================================

A similar process is used for overriding things when building the Exim
monitor, where the files that are involved are

     OS/eximon.conf-Default
     OS/eximon.conf-<ostype>
     Local/eximon.conf
     Local/eximon.conf-<ostype>
     Local/eximon.conf-<archtype>
     Local/eximon.conf-<ostype>-<archtype>

As with Exim itself, the final three files need not exist, and in this
case the `OS/eximon.conf-<ostype>' file is also optional. The default
values in `OS/eximon.conf-Default' can be overridden dynamically by
setting environment variables of the same name, preceded by EXIMON_.
For example, setting EXIMON_LOG_DEPTH in the environment overrides the
value of LOG_DEPTH at run time.


File: exim.info,  Node: Installing commands and scripts,  Next: Installing info documentation,  Prev: Overriding build-time options for the monitor,  Up: Building and installing Exim

Installing commands and scripts
===============================

The script `scripts/exim_install' copies binaries and utility scripts
into the directory whose name is specified by the BIN_DIRECTORY setting
in `Local/Makefile'. Files are copied only if they are newer than any
versions already in the binary directory, and old versions are renamed
by adding the suffix `.O' to their names.

The command "make install" runs the "exim_install" script with no
arguments.  It can be run independently with arguments specifying which
files are to be copied, from within a build directory. For example,

     (cd build-SunOS5-sparc; ../scripts/exim_install exim)

copies just the main binary file. The main "exim" binary is required to
be owned by root and setuid, for normal configurations. In some special
cases (for example, if a host is doing no local deliveries) is is
possible to run Exim in other ways. If the binary is run by a root
process, the effect is the same as if it were setuid root.  The install
script tries to set root as the owner of the main binary, and to make
it setuid. It should therefore normally be run as root. If you want to
see what the script will do before running it for real, use the -n
option (for which root is not needed):

     (cd build-SunOS5-5.5.1-sparc; ../scripts/exim_install -n)

Exim's run time configuration file is named by the CONFIGURE_FILE
setting in `Local/Makefile'. If this file does not exist, the default
configuration file `src/configure.default' is copied there by the
installation script. If a run time configuration file already exists,
it is left alone. The default configuration uses the local host's name
as the only local domain, and is set up to do local deliveries into the
shared directory `/var/mail', running as the local user. Aliases in
`/etc/aliases' and `.forward' files in users' home directories are
supported, but no NIS or NIS+ support is configured. Remote domains are
routed using the DNS, with delivery over SMTP.


File: exim.info,  Node: Installing info documentation,  Next: Setting up the spool directory,  Prev: Installing commands and scripts,  Up: Building and installing Exim

Installing info documentation
=============================

Not all systems use the GNU "info" system for documentation, and for
this reason, the Texinfo source of Exim's documentation is not included
in the main distribution. Instead it is available separately from the
ftp site (see section "Availability" in chapter "Introduction").

If you have defined INFO_DIRECTORY in `Local/Makefile' and the Texinfo
source of the documentation is found in the source tree, running "make
install" automatically builds the info files and installs them.


File: exim.info,  Node: Setting up the spool directory,  Next: Testing,  Prev: Installing info documentation,  Up: Building and installing Exim

Setting up the spool directory
==============================

When it starts up, Exim tries to create its spool directory if it does
not exist. If a specific Exim uid and gid are specified, these are used
for the owner and group of the spool directory. Sub-directories are
automatically created in the spool directory as necessary.


File: exim.info,  Node: Testing,  Next: Switching Exim on,  Prev: Setting up the spool directory,  Up: Building and installing Exim

Testing
=======

Having installed Exim, you can check that the run time configuration
file is syntactically valid by running the command

     exim -bV

If there are any errors in the configuration file, Exim will output
error messages. Otherwise it just outputs the version number and build
date. Some simple routing tests can be done by using the address
testing option. For example,

     exim -v -bt <local username>

should verify that it recognizes a local mailbox, and

     exim -v -bt <remote address>

a remote one. Then try getting it to deliver mail, both locally and
remotely.  This can be done by passing messages directly to Exim,
without going through a user agent. For example:

     exim postmaster@your.domain
     From: user@your.domain
     To: postmaster@your.domain
     Subject: Testing Exim
     
     This is a test message.
     ^D

If you encounter problems, look at Exim's log files ("mainlog" and
"paniclog") to see if there is any relevant information there. Another
source of information is running Exim with debugging turned on, by
specifying the -d option. The larger the number after -d (up to 9), the
more information is output. With -d2, for example, the sequence of
directors or routers that process an address is output. If there's a
message stuck on Exim's spool, you can force a delivery with debugging
turned on by a command of the form

     exim -d9 -M <message-id>

One specific problem that has shown up on some sites is the inability
to do local deliveries into a single shared mailbox directory that does
not have the `sticky bit' set on it. By default, Exim tries to create a
lock file before writing to a mailbox file, and if it cannot create the
lock file, the delivery is deferred. You can get round this either by
setting the `sticky bit' on the directory, or by setting a specific
group for local deliveries and allowing that group to create files in
the directory (see the comments above the "local_delivery" transport in
the default configuration file). Another approach is to configure Exim
not to use lock files, but just to rely on "fcntl()" locking instead.
However, you should do this only if all user agents also use "fcntl()"
locking. For further discussion of locking issues, see chapter "The
appendfile transport".

One thing that cannot be tested on a system that is already running a
mailer is the receipt of incoming SMTP mail on the standard SMTP port.
However, the -oX option can be used to run an Exim daemon that listens
on some other port, or "inetd" can be used to do this.  The -bh option
can be used to check out any policy controls on incoming SMTP mail.

Testing a new version on a system that is already running Exim can most
easily be done by building a binary with a different CONFIGURE_FILE
setting. From within the run time configuration, all other file and
directory names that Exim uses can be altered, in order to keep it
entirely clear of the production version.


File: exim.info,  Node: Switching Exim on,  Next: Exim on heavily loaded hosts,  Prev: Testing,  Up: Building and installing Exim

Switching Exim on
=================

Building and installing Exim does not of itself put it in general use.
The name by which the system message transfer agent is called by mail
user agents is either `/usr/lib/sendmail', or `/usr/sbin/sendmail'
(depending on the operating system), and it is necessary to make this
name point to the "exim" binary in order to get them to use it. This is
normally done by renaming any existing file and making
`/usr/lib/sendmail' or `/usr/sbin/sendmail' a symbolic link to the
"exim" binary. It is a good idea to remove any setuid privilege and
executable status from the old MTA. It is then necessary to stop and
restart the mailer daemon, if one is running.

You should consider what to tell your users about the change of MTA.
Exim may have different capabilities to what was previously running,
and there are various operational differences such as the text of
messages produced by command line options and in bounce messages. If
you allow your users to make use of Exim's filtering capabilities, you
should make the document entitled "Exim's interface to mail filtering"
available to them.


File: exim.info,  Node: Exim on heavily loaded hosts,  Next: Stopping Exim on Solaris,  Prev: Switching Exim on,  Up: Building and installing Exim

Exim on heavily loaded hosts
============================

If you are running Exim on a heavily loaded host you should consider
installing a current release of "bind" (from http://www.isc.org) as
caching nameserver, either locally or on a nearby host with a fast
network connection. You should also consider enabling Exim's
"split_spool_directory" if you expect to have large numbers of messages
awaiting delivery.


File: exim.info,  Node: Stopping Exim on Solaris,  Prev: Exim on heavily loaded hosts,  Up: Building and installing Exim

Stopping Exim on Solaris
========================

The standard command for stopping the mailer daemon on Solaris is

     /etc/init.d/sendmail stop

If `/usr/lib/sendmail' has been turned into a symbolic link, this
script fails to stop Exim because it uses the command "ps -e" and greps
the output for the text `sendmail'; this is not present because the
actual program name (that is, `exim') is given by the "ps" command with
these options.  A fix that appears to work on Solaris 2.5 and above is
to change the script so that the "ps" command reads

     ps -e -o pid,comm

which causes the name by which the daemon was started (that is,
`/usr/lib/sendmail') to be output. However, this fails if the daemon
has been restarted with SIGHUP because Exim restarts itself using the
real file name. A better solution is to replace the line that finds the
process id with something like

     pid=`cat /var/spool/exim/exim-daemon.pid`

to obtain the daemon's pid directly from the file that Exim saves it in.
See the description of the -bd option for details of where Exim writes
the daemon's process id file.


File: exim.info,  Node: The Exim command line,  Next: File and database lookups,  Prev: Building and installing Exim,  Up: Top

The Exim command line
*********************

Exim's command line takes the standard Unix form of a sequence of
options, each starting with a hyphen character, followed by a number of
arguments. The options are compatible with the main options of
Sendmail, and there are also some additional options, some of which are
compatible with Smail 3. Certain combinations of options do not make
sense, and provoke an error if used.  The form of the arguments depends
on which options are set.



* Menu:

* Setting options by program name::
* Trusted and admin users::
* Command line options::


File: exim.info,  Node: Setting options by program name,  Next: Trusted and admin users,  Prev: The Exim command line,  Up: The Exim command line

Setting options by program name
===============================

If Exim is called under the name "mailq", it behaves as if the option
-bp were present before any other options. This is for compatibility
with some systems that contain a command of that name in one of the
standard libraries, symbolically linked to `/usr/lib/sendmail' or
`/usr/sbin/sendmail'.

If Exim is called under the name "rsmtp" it behaves as if the option
-bS were present before any other options, for compatibility with
Smail. The -bS option is used for reading in a number of messages in
batched SMTP format.

If Exim is called under the name "rmail" it behaves as if the -i and
-oee options were present before any other options, for compatibility
with Smail.  The name "rmail" is used as an interface by some UUCP
systems.

If Exim is called under the name "runq" it behaves as if the option -q
were present before any other options, for compatibility with Smail.
The -q option causes a single queue-runner process to be started.

If Exim is called under the name "newaliases" it behaves as if the
option -bi were present before any other options, for compatibility
with Sendmail. This option is used for rebuilding Sendmail's alias
file. Exim does not have the concept of a single alias file, but can be
configured to run a given command if called with the -bi option.


File: exim.info,  Node: Trusted and admin users,  Next: Command line options,  Prev: Setting options by program name,  Up: The Exim command line

Trusted and admin users
=======================

Some Exim options are available only to "trusted users" and others are
available only to "admin users". In the description below, the phrases
`Exim user' and `Exim group' mean the user and group defined by
EXIM_UID and EXIM_GID in `Local/Makefile' or set by the "exim_user" and
"exim_group" options. These do not necessarily have to use the name
`exim'.

   * A trusted user is root or the Exim user or any user listed in the
     "trusted_users" configuration option, or any user for whom the
     currently set group is the Exim group (if defined) or whose
     current group or any supplementary group is one of those listed in
     the "trusted_groups" configuration option.

     Trusted users are always permitted to use the -f option or a
     leading `From ' line to specify the envelope sender of a message
     that is passed to Exim through the local interface (see the -bm
     and -f options below). For a trusted user, there is never any
     check on the contents of the "From:" header line, and a "Sender:"
     line is never added. Furthermore, any existing "Sender:" line in
     incoming local (non-TCP/IP) messages is not removed.

     Trusted users may also specify a host name, host address,
     interface address, protocol name, and ident value. Thus they are
     able to insert messages into Exim's queue locally that have the
     characteristics of messages received from a remote host.
     Untrusted users may in some circumstances use -f, but can never
     set the other values that trusted users can.

     "From:" headers are not checked to see if "Sender:" is needed when
     the caller is trusted.

   * An admin user is root or the Exim user or any user that is a
     member of the Exim group (if defined), or of any group listed in
     the "admin_groups" configuration option. The current group does
     not have to be one of these groups.

     Admin users are permitted to operate on messages in the queue, for
     example, to force delivery failures. It is also necessary to be an
     admin user in order to see the full information provided by the
     Exim monitor, and full debugging output.

     By default, the use of the -M, -q, -R, and -S options to cause
     Exim to attempt delivery of messages on its queue is restricted to
     admin users.  However, this restriction can be relaxed by setting
     the "prod_requires_admin" option false (that is, specifying
     "no_prod_requires_admin").

     Similarly, the use of the -bp option to list all the messages in
     the queue is restricted to admin users unless
     "queue_list_requires_admin" is set false.


File: exim.info,  Node: Command line options,  Prev: Trusted and admin users,  Up: The Exim command line

Command line options
====================

The command options are described in alphabetical order below.



* Menu:

* -<hyphen>::
* -B<type>::
* -bd::
* -be::
* -bF <filename>::
* -bf <filename>::
* -bh <IP address>::
* -bi::
* -bm::
* -bp::
* -bpa::
* -bpc::
* -bpr::
* -bpra::
* -bpru::
* -bpu::
* -bP::
* -brt::
* -brw::
* -bS::
* -bs::
* -bt::
* -bV::
* -bv::
* -bvs::
* -C <filename>::
* -D<macro>=<value>::
* -d<number>::
* -df::
* -dm::
* -dropcr::
* -E::
* -ex::
* -F <string>::
* -f <address>::
* -h <number>::
* -i::
* -M <message id> <message id>::
* -Mar <message id> <address> <address>::
* -MC <transport> <hostname> <sequence number> <message id>::
* -MCA::
* -MCQ <process id> <pipe fd>::
* -MCS::
* -MCT::
* -Mc <message id> <message id>::
* -Meb <message id>::
* -Mes <message id> <address>::
* -Mf <message id> <message id>::
* -Mg <message id> <message id>::
* -Mmad <message id> <message id>::
* -Mmd <message id> <address> <address>::
* -Mrm <message id> <message id>::
* -Mt <message id> <message id>::
* -Mvb <message id>::
* -Mvh <message id>::
* -Mvl <message id>::
* -m::
* -N::
* -n::
* -oA <file name>::
* -oB <n>::
* -odb::
* -odf::
* -odi::
* -odq::
* -odqr::
* -odqs::
* -oee::
* -oem::
* -oep::
* -oeq::
* -oew::
* -oi::
* -oitrue::
* -oMa <host address>::
* -oMas <address>::
* -oMai <string>::
* -oMi <interface address>::
* -oMr <protocol name>::
* -oMs <host name>::
* -oMt <ident string>::
* -om::
* -oo::
* -or <time>::
* -ov::
* -oX <number>::
* -pd::
* -ps::
* -q::
* -q <time>::
* -qf::
* -qff::
* -qfl::
* -qffl::
* -ql::
* -qq::
* -qR<flags> <string>::
* -qS<flags> <string>::
* -R<flags> <string>::
* -r::
* -S<flags> <string>::
* -t::
* -U::
* -v::
* -x::


File: exim.info,  Node: -<hyphen>,  Next: -B<type>,  Prev: Command line options,  Up: Command line options

-- _option_
-----------

This option consists of two consecutive hyphens. It appears in the menu
as "-<hyphen>" because otherwise Texinfo gets confused with its
cross-referencing.  This is a pseudo-option whose only purpose is to
terminate the options and therefore to cause subsequent command line
items to be treated as arguments rather than options, even if they
begin with hyphens.


File: exim.info,  Node: -B<type>,  Next: -bd,  Prev: -<hyphen>,  Up: Command line options

-B<type> _option_
-----------------

This is a Sendmail option for selecting 7 or 8 bit processing. Exim is
entirely 8-bit clean; it ignores this option.


File: exim.info,  Node: -bd,  Next: -be,  Prev: -B<type>,  Up: Command line options

-bd _option_
------------

Run Exim as a daemon, awaiting incoming SMTP connections. This option
can be used only by an admin user. If either of the -d or -dm options
are set, the daemon does not disconnect from the controlling terminal.
By default, Exim listens for incoming connections on all the host's
interfaces, but it can be restricted to specific interfaces by setting
the "local_interfaces" option in the configuration file. The standard
SMTP port is used, but this can be varied by means of the
"daemon_smtp_port" configuration option or the -oX command line option.
Most commonly, the -bd option is combined with the -q<time> option, to
cause periodic queue runs to happen as well.

The process id of a daemon that is both listening on the standard SMTP
port and periodically starting queue runners is written to a file called
`exim-daemon.pid' in Exim's spool directory. If a non-standard port is
used, the file name is `exim-daemon.<port-number>.pid'. If a daemon is
run with only one of -bd or -q<time>, that option is added on to the
end of the file name, allowing sites that run two separate daemons to
distinguish them.

It is possible to change the directory in which these pid files are
written by changing the setting of PID_FILE_PATH in `Local/Makefile'.
The files are written while Exim is still running as root. Further
details are given in the comments in `src/EDITME'.

The SIGHUP signal can be used to cause the daemon to re-exec itself.
This should be done whenever Exim's configuration file is changed, or a
new version of Exim is installed. It is not necessary to do this when
other files (for example, alias files) are changed.


File: exim.info,  Node: -be,  Next: -bF <filename>,  Prev: -bd,  Up: Command line options

-be _option_
------------

Run Exim in expansion testing mode.  Exim discards its root privilege,
to prevent ordinary users from using this mode to read otherwise
inaccessable files.  If no arguments are given, it runs interactively,
prompting for lines of data.  Each argument (or data line) is passed
through the string expansion mechanism, and the result is output.
Variable values from the configuration file (for example,
$qualify_domain) are available, but no message-specific values (such as
$domain) are set because no message is being processed.


File: exim.info,  Node: -bF <filename>,  Next: -bf <filename>,  Prev: -be,  Up: Command line options

-bF <filename> _option_
-----------------------

This option is the same as -bf except that it assumes that the filter
being tested is a system filter. The additional commands that are
available only in system filters are recognized.


File: exim.info,  Node: -bf <filename>,  Next: -bh <IP address>,  Prev: -bF <filename>,  Up: Command line options

-bf <filename> _option_
-----------------------

Run Exim in filter testing mode; the file is the filter file to be
tested, and a test message must be supplied on the standard input. If
there are no message-dependent tests in the filter, an empty file can
be supplied.  If a system filter file is being tested, -bF should be
used instead of -bf. If the test file does not begin with the special
line

     # Exim filter

then it is taken to be a normal `.forward' file, and is tested for
validity under that interpretation. The result of this command,
provided no errors are detected, is a list of the actions that Exim
would try to take if presented with the message for real. More details
of filter testing are given in the separate document entitled "Exim's
interface to mail filtering".

When testing a filter file, the envelope sender can be set by the -f
option, or by a `From ' line at the start of the test message. Various
parameters that would normally be taken from the envelope recipient
address of the message can be set by means of additional command line
options. These are:

     -bfd             <domain>               default is the qualify domain
     -bfl             <local_part>           default is the logged in user
     -bfp             <local_part_prefix>    default is null
     -bfs             <local_part_suffix>    default is null

The local part should always be set to the incoming address with any
prefix or suffix stripped, because that is how it appears when a
message is actually being delivered.


File: exim.info,  Node: -bh <IP address>,  Next: -bi,  Prev: -bf <filename>,  Up: Command line options

-bh <IP address> _option_
-------------------------

This option runs a fake SMTP session as if from the given IP address,
using the standard input and output.  The IP address may include a port
number at the end, after full stop. For example:

     exim -bh 10.9.8.7.1234
     exim -bh fe80::a00:20ff:fe86:a061.5678

Comments as to what is going on are written to the standard error file.
These include lines beginning with `LOG' for anything that would have
been logged.  This facility is for testing configuration options for
blocking hosts and/or senders and for checking on relaying control.
Messages supplied during the testing session are discarded, and nothing
is written to any of the real log files. There may be pauses when DNS
(and other) lookups are taking place, and of course these may time out.
The -oMi option can be used to specify a specific IP interface if this
is important.


File: exim.info,  Node: -bi,  Next: -bm,  Prev: -bh <IP address>,  Up: Command line options

-bi _option_
------------

Sendmail interprets the -bi option as a request to rebuild its alias
file.  Exim does not have the concept of a single alias file, and so it
cannot mimic this behaviour. However, calls to "/usr/lib/sendmail -bi"
tend to appear in various scripts such as NIS make files, so the option
must be recognized.

If -bi is encountered, the command specified by the "bi_command"
configuration option is run, under the uid and gid of the caller of
Exim. If the -oA option is used, its value is passed to the command as
an argument.  The command set by "bi_command" may not contain
arguments. The command can use the "exim_dbmbuild" utility, or some
other means, to rebuild alias files if this is required. If the
"bi_command" option is not set, calling Exim with -bi is a no-op.


File: exim.info,  Node: -bm,  Next: -bp,  Prev: -bi,  Up: Command line options

-bm _option_
------------

Accept an incoming, locally-generated message on the current input, and
deliver it to the addresses given as the command arguments (except when
-t is also given - see below). Each argument can be a comma-separated
list of RFC 822 addresses. This is the default option for selecting the
overall action of an Exim call; it is assumed if no other conflicting
option is present.

The format of the message must be as defined in RFC 822, except that,
for compatibility with Sendmail and Smail, a line in one of the forms

     From sender Fri Jan  5 12:55 GMT 1997
     From sender Fri, 5 Jan 97 12:55:01

(with the weekday optional, and possibly with additional text after the
date) is permitted to appear at the start of the message. There appears
to be no authoritative specification of the format of this line. Exim
recognizes it by matching against the regular expression defined by the
"uucp_from_pattern" option, which can be changed if necessary. The
specified sender is treated as if it were given as the argument to the
-f option, but if a -f option is also present, its argument is used in
preference to the address taken from the message. The caller of Exim
must be a trusted user for the sender of a message to be set in this
way.


File: exim.info,  Node: -bp,  Next: -bpa,  Prev: -bm,  Up: Command line options

-bp _option_
------------

List the contents of the mail queue on the standard output. If the -bp
option is followed by a list of message ids, just those messages are
listed.  By default, this option can be used only by an admin user.
However, the "queue_list_requires_admin" option can be set false to
allow any user to see the queue.

Each message on the queue is displayed as in the following example:

     25m  2.9K 0t5C6f-0000c8-00 <alice@wonderland.fict.book>
               red.king@looking-glass.fict.book
               <other addresses>

The first line contains the length of time the message has been on the
queue (in this case 25 minutes), the size of the message (2.9K), the
unique local identifier for the message, and the message sender, as
contained in the envelope. If the message is a delivery error message,
the sender address is empty, and appears as `<>'.  If the message was
submitted locally by an untrusted user who overrode the default sender
address, the user's login name is shown in parentheses before the
sender address.  If the message is frozen (attempts to deliver it are
suspended) then the text `*** frozen ***' is displayed at the end of
this line.

The recipients of the message (taken from the envelope, not the
headers) are displayed on subsequent lines. Those addresses to which
the message has already been delivered are marked with the letter D. If
an original address gets expanded into several addresses via an alias
or forward file, the original is displayed with a D only when
deliveries for all of its child addresses are complete.


File: exim.info,  Node: -bpa,  Next: -bpc,  Prev: -bp,  Up: Command line options

-bpa _option_
-------------

This option operates like -bp, but in addition it shows delivered
addresses that were generated from the original top level address(es)
in each message by alias or forwarding operations. These addresses are
flagged with `+D' instead of just `D'.


File: exim.info,  Node: -bpc,  Next: -bpr,  Prev: -bpa,  Up: Command line options

-bpc _option_
-------------

This option counts the number of messages on the queue, and writes the
total to the standard output. It is restricted to admin users, unless
"queue_list_requires_admin" is set false.


File: exim.info,  Node: -bpr,  Next: -bpra,  Prev: -bpc,  Up: Command line options

-bpr _option_
-------------

This option operates like -bp, but the output is not sorted into
chronological order of message arrival. This can speed it up when there
are lots of messages on the queue, and is particularly useful if the
output is going to be post-processed in a way that doesn't need the
sorting.


File: exim.info,  Node: -bpra,  Next: -bpru,  Prev: -bpr,  Up: Command line options

-bpra _option_
--------------

This option is a combination of -bpr and -bpa.


File: exim.info,  Node: -bpru,  Next: -bpu,  Prev: -bpra,  Up: Command line options

-bpru _option_
--------------

This option is a combination of -bpr and -bpu.


File: exim.info,  Node: -bpu,  Next: -bP,  Prev: -bpru,  Up: Command line options

-bpu _option_
-------------

This option operates like -bp but shows only undelivered top-level
addresses for each message displayed. Addresses generated by aliasing
or forwarding are not shown, unless the message was deferred after
processing by a director with the "one_time" option set.


File: exim.info,  Node: -bP,  Next: -brt,  Prev: -bpu,  Up: Command line options

-bP _option_
------------

If this option is given with no arguments, it causes the values of all
Exim's main configuration options to be written to the standard output.
The values of one or more specific options can be requested by giving
their names as arguments, for example:

     exim -bP qualify_domain local_domains

However, any configuration setting that was preceded by the word `hide'
is not shown in full, except to an admin user. For other users, output
such as

     mysql_servers = <value not displayable>

is used.  If "configure_file" is given as an argument, the name of the
run time configuration file is output.  If "log_file_path" or
"pid_file_path" are given, the names of the directories where log files
and daemon pid files are written are output, respectively. If these
values are unset, log files are written in a sub-directory of the spool
directory called "log", and pid files are written directly into the
spool directory.

If one of the words "director", "router", "transport", or
"authenticator" is given, followed by the name of an appropriate driver
instance, the option settings for that driver are output. For example:

     exim -bP transport local_delivery

The generic driver options are output first, followed by the driver's
private options. A list of the names of drivers of a particular type
can be obtained by using one of the words "director_list",
"router_list", "transport_list", or "authenticator_list", and a
complete list of all drivers with their option settings can be obtained
by using "directors", "routers", "transports", or "authenticators".


File: exim.info,  Node: -brt,  Next: -brw,  Prev: -bP,  Up: Command line options

-brt _option_
-------------

This option is for testing retry rules, and it must be followed by up
to three arguments. It causes Exim to look for a retry rule that
matches the values and to write it to the standard output. For example:

     exim -brt bach.comp.mus
     Retry rule: *.comp.mus  F,2h,15m; FG,4d,30m;

See chapter "Retry configuration" for a description of Exim's retry
rules. The first argument, which is required, can be a complete address
in the form "local_part@domain", or it can be just a domain name. The
second argument is an optional second domain name; if no retry rule is
found for the first argument, the second is tried. This ties in with
Exim's behaviour when looking for retry rules for remote hosts - if no
rule is found that matches the host, one that matches the mail domain
is sought. The final argument is the name of a specific delivery error,
as used in setting up retry rules, for example `quota_3d'.


File: exim.info,  Node: -brw,  Next: -bS,  Prev: -brt,  Up: Command line options

-brw _option_
-------------

This option is for testing address rewriting rules, and it must be
followed by a single argument, consisting of either a local part
without a domain, or a complete address with a fully qualified domain.
Exim outputs how this address would be rewritten for each possible
place it might appear. See chapter "Address rewriting" for further
details.


File: exim.info,  Node: -bS,  Next: -bs,  Prev: -brw,  Up: Command line options

-bS _option_
------------

This option is used for batched SMTP input, where messages have been
received from some external source by an alternative transport
mechanism. It causes Exim to accept one or more messages by reading
SMTP on the standard input, but to generate no responses.  If any error
is encountered reports are written to the standard output and error
streams, and Exim gives up immediately.

If the caller is trusted, or "untrusted_set_sender" is set, the senders
in the MAIL commands are believed; otherwise the sender is always the
caller of Exim. Unqualified senders and receivers are not rejected
(there seems little point) but instead just get qualified. Sender
addresses are verified if "sender_verify" is set, unless
"sender_verify_batch" is unset (which is the default). Receiver
verification and administrative rejection is not done, even if
configured. HELO and EHLO act as RSET; VRFY, EXPN, ETRN, HELP, and
DEBUG act as NOOP; QUIT quits.  The return code is 0 if no error was
detected; it is 1 if one or more messages were accepted before the
error was detected; otherwise it is 2. More details of input using
batched SMTP are given in section "Incoming batched SMTP" in chapter
"SMTP processing".


File: exim.info,  Node: -bs,  Next: -bt,  Prev: -bS,  Up: Command line options

-bs _option_
------------

This option causes Exim to accept one or more messages by reading SMTP
commands on the standard input, and producing SMTP replies on the
standard output. Some user agents use this interface as a way of
passing locally-generated messages to the MTA. The option can also be
used to run Exim from "inetd", as an alternative to using a listening
daemon, in which case the standard input is the connected socket. Exim
distinguishes between the two cases by attempting to read the IP
address of the peer connected to the standard input. If it is not a
socket, the call to "getpeername()" fails, and Exim assumes it is
dealing with a local message.

If the caller of Exim is trusted, or "untrusted_set_sender" is set, the
senders of messages are taken from the SMTP MAIL commands. Otherwise
the content of these commands is ignored and the sender is set up as
the calling user.


File: exim.info,  Node: -bt,  Next: -bV,  Prev: -bs,  Up: Command line options

-bt _option_
------------

Run in address testing mode, in which each argument is taken as an
address to be tested. The results are written to the standard output.
If no arguments are given, Exim runs in an interactive manner,
prompting with a right angle bracket for addresses to be tested. Each
address is handled as if it were the recipient address of a message and
passed to the appropriate directors or routers (compare the -bv
option); the result is written to the standard output. The return code
is 2 if any address failed outright; it is 1 if no address failed
outright but at least one could not be resolved for some reason. Return
code 0 is given only when all addresses succeed.

Warning: -bt can only do relatively simple testing. If any of the
directors or routers in the configuration makes any tests on the sender
address of a message, you can use the -f option to set an appropriate
sender when running -bt tests. Without it, the sender is assumed to be
the calling user at the default qualifying domain. However, if you have
set up (for example) directors and routers whose behaviour depends on
the contents of an incoming message, you cannot test those conditions
using -bt. The -N option provides a possible way of doing such tests.


File: exim.info,  Node: -bV,  Next: -bv,  Prev: -bt,  Up: Command line options

-bV _option_
------------

Write the current version number, compilation number, and compilation
date of the "exim" binary to the standard output.


File: exim.info,  Node: -bv,  Next: -bvs,  Prev: -bV,  Up: Command line options

-bv _option_
------------

Verify the addresses that are given as the arguments to the command,
and write the results to the standard output.  If no arguments are
given, Exim runs in an interactive manner, prompting with a right angle
bracket for addresses to be tested.  Verification differs from address
testing (the -bt option) in that directors and routers that have
"no_verify" set are skipped, and if the address is accepted by a
director or router that has "fail_verify" set, verification fails. This
is the same logic that is used when verifying addresses of incoming
messages (see chapter "Verification of incoming mail"). The address is
verified as a recipient if -bv is used; to verify as for a sender
address, -bvs should be used.

If the -v (or -d) option is not set, the output consists of a single
line for each address, stating whether it was verified or not, and
giving a reason in the latter case. Otherwise, more details are given
of how the address has been handled, and in the case of aliases or
forwarding, all the generated addresses are also considered. Otherwise,
generating an address by forwarding, or more than one address by
aliasing, causes verification to end sucessfully.

The return code is 2 if any address failed outright; it is 1 if no
address failed outright but at least one could not be resolved for some
reason. Return code 0 is given only when all addresses succeed.

If any of the directors or routers in the configuration makes any tests
on the sender address of a message, you should use the -f option to set
an appropriate sender when running -bv tests. Without it, the sender is
assumed to be the calling user at the default qualifying domain.


File: exim.info,  Node: -bvs,  Next: -C <filename>,  Prev: -bv,  Up: Command line options

-bvs _option_
-------------

This option acts like -bv, but verifies the address as a sender rather
than a recipient address. This affects any rewriting and qualification
that might happen.


File: exim.info,  Node: -C <filename>,  Next: -D<macro>=<value>,  Prev: -bvs,  Up: Command line options

-C <filename> _option_
----------------------

Read the run time configuration from the given file instead of from the
default file specified by the CONFIGURE_FILE compile-time setting. When
this option is used by an unprivileged caller and the file name given
is different from the compiled-in name, Exim gives up its root
privilege immediately, and runs with the real and effective uid and gid
set to those of the caller, to avoid any security exposure. It does not
do this if the caller is root or the Exim user defined by EXIM_UID in
`Local/Makefile'.  The facility is useful for ensuring that
configuration files are syntactically correct, but cannot be used for
test deliveries, unless the caller is privileged, or unless it's an
exotic configuration that does not require privilege. No check is made
on the owner or group of the file specified by this option.


File: exim.info,  Node: -D<macro>=<value>,  Next: -d<number>,  Prev: -C <filename>,  Up: Command line options

-D<macro>=<value> _option_
--------------------------

This option can be used to override macro definitions in the
configuration file (see section "Macros in the configuration file" in
chapter "The Exim configuration file"). However, like -C, if it is used
by an unprivileged caller, it causes Exim to give up its root privilege.
This option may be repeated up to 10 times on a command line.


File: exim.info,  Node: -d<number>,  Next: -df,  Prev: -D<macro>=<value>,  Up: Command line options

-d<number> _option_
-------------------

Set a debug level, causing debugging information to be written to the
standard error file. White space between -d and the number is optional.
If no number is given, 1 is assumed, and the higher the number, the
more output is produced.  A value of zero turns debugging output off
and is the default. A value of 9 gives the maximum amount of general
information, 10 gives in addition details of the interpretation of
filter files, and 11 or higher also turns on the debugging option for
DNS lookups.

For non-admin users, the number is ignored, and a debug level of 1 is
always used. This restriction exists because debugging output may show
database queries that contain password information, and also the
details of users' filter files should be protected.


File: exim.info,  Node: -df,  Next: -dm,  Prev: -d<number>,  Up: Command line options

-df _option_
------------

If this option is set and STDERR_FILE was defined when Exim was built,
debugging information is written to the file defined by that variable
instead of to the standard error file. This option provides a way of
obtaining debugging information when Exim is run from "inetd".


File: exim.info,  Node: -dm,  Next: -dropcr,  Prev: -df,  Up: Command line options

-dm _option_
------------

This option causes information about memory allocation and freeing
operations to be written to the standard error file.


File: exim.info,  Node: -dropcr,  Next: -E,  Prev: -dm,  Up: Command line options

-dropcr _option_
----------------

At least one MUA (dtmail) that calls an MTA via the command line is
broken in that it terminates each line with CRLF, instead of just LF,
which is the usual Unix convention, and although this bug has been
admitted, it apparently won't get fixed. There is also some UUCP
software which leaves CR at the ends of lines in messages. As a slight
pander to these programs, the -dropcr option causes Exim to drop all CR
characters in an incoming non-SMTP message.


File: exim.info,  Node: -E,  Next: -ex,  Prev: -dropcr,  Up: Command line options

-E _option_
-----------

This option specifies that an incoming message is a locally-generated
delivery failure report. It is used internally by Exim when handling
delivery failures and is not intended for external use. Its only effect
is to stop Exim generating certain messages to the mailmaster, as
otherwise message cascades could occur in some situations. As part of
the same option, a message id may follow the characters -E. If it does,
the log entry for the receipt of the new message contains the id,
following `R=', as a cross-reference.


File: exim.info,  Node: -ex,  Next: -F <string>,  Prev: -E,  Up: Command line options

-ex _option_
------------

There are a number of Sendmail options starting with -oe which seem to
be called by various programs without the leading "o" in the option.
For example, the "vacation" program uses -eq. Exim treats all options
of the form -ex as synonymous with the corresponding -oex options.


File: exim.info,  Node: -F <string>,  Next: -f <address>,  Prev: -ex,  Up: Command line options

-F <string> _option_
--------------------

Set the sender's full name for use when a locally-generated message is
being accepted. In the absence of this option, the user's "gecos" entry
from the password file is used. As users are generally permitted to
alter their "gecos" entries, no security considerations are involved.
White space between -F and the <string> is optional.


File: exim.info,  Node: -f <address>,  Next: -h <number>,  Prev: -F <string>,  Up: Command line options

-f <address> _option_
---------------------

Set the address of the envelope sender of a locally-generated message
(also known as the return path). This option can normally be used only
by root or the Exim user or by one of the configured trusted users, but
if "untrusted_set_sender" is set, its use is not restricted. However,
even when "untrusted_set_sender" is not set, anyone may use it when
testing a filter file with -bf or when testing or verifying addresses
using the -bt or -bv options. There is also no restriction of the use
of the special setting -f <> to send a message with an empty sender;
such a message can never provoke a bounce. In other cases, the sender
of a local message is set up as the user who ran the "exim" command,
and -f is ignored,

Allowing untrusted users to change the sender address does not of
itself make it possible to send anonymous mail. Exim still checks that
the "From:" header refers to the local user, and if it does not, it
adds a "Sender:" header, though this can be overridden by setting
"no_local_from_check".

White space between -f and the <address> is optional. The sender of a
locally-generated message can also be set (when permitted) by an initial
`From ' line in the message - see the description of -bm above, but if
-f is also present, it overrides `From '.


File: exim.info,  Node: -h <number>,  Next: -i,  Prev: -f <address>,  Up: Command line options

-h <number> _option_
--------------------

This option is accepted for compatibility with Sendmail, but at present
has no effect. (In Sendmail it overrides the `hop count' obtained by
counting "Received:" headers.)


File: exim.info,  Node: -i,  Next: -M <message id> <message id>,  Prev: -h <number>,  Up: Command line options

-i _option_
-----------

This option, which has the same effect as -oi, specifies that a dot on
a line by itself should not terminate an incoming, non-SMTP message. I
can find no documentation for this option in Solaris 2.4 Sendmail, but
the "mailx" command in Solaris 2.4 uses it.


File: exim.info,  Node: -M <message id> <message id>,  Next: -Mar <message id> <address> <address>,  Prev: -i,  Up: Command line options

-M <message id> <message id> _option_
-------------------------------------

Exim runs a delivery attempt on each message in turn. If any of the
messages are frozen, they are automatically thawed before the delivery
attempt. The settings of "queue_remote_domains", "queue_smtp_domains",
and "hold_domains" are ignored. Retry hints for any of the addresses are
overridden - Exim tries to deliver even if the normal retry time has
not yet been reached. This option requires the caller to be an admin
user. However, there is an option called "prod_requires_admin" which
can be set false to relax this restriction (and also the same
requirement for the -q, -R, and -S options).


File: exim.info,  Node: -Mar <message id> <address> <address>,  Next: -MC <transport> <hostname> <sequence number> <message id>,  Prev: -M <message id> <message id>,  Up: Command line options

-Mar <message id> <address> <address> _option_
----------------------------------------------

The first argument must be a message id, and the remaining ones must be
email addresses. Exim adds the addresses to the list of recipients of
the message (`ar' for `add recipients'). However, if the message is
active (in the middle of a delivery attempt), its status is not
altered. This option can be used only by an admin user.


File: exim.info,  Node: -MC <transport> <hostname> <sequence number> <message id>,  Next: -MCA,  Prev: -Mar <message id> <address> <address>,  Up: Command line options

-MC <transport> <hostname> <sequence number> <message id> _option_
------------------------------------------------------------------

This option is not intended for use by external callers. It is used
internally by Exim to invoke another instance of itself to deliver a
waiting message using an existing SMTP channel, which is passed as the
standard input. Details are given in chapter "SMTP processing". This
must be the final option, and the caller must be root or the Exim user
in order to use it.


File: exim.info,  Node: -MCA,  Next: -MCQ <process id> <pipe fd>,  Prev: -MC <transport> <hostname> <sequence number> <message id>,  Up: Command line options

-MCA _option_
-------------

This option is not intended for use by external callers. It is used
internally by Exim in conjunction with -MC option. It signifies that
the connection to the remote host has been authenticated.


File: exim.info,  Node: -MCQ <process id> <pipe fd>,  Next: -MCS,  Prev: -MCA,  Up: Command line options

-MCQ <process id> <pipe fd> _option_
------------------------------------

This option is not intended for use by external callers. It is used
internally by Exim in conjunction with -MC option when the original
delivery was started by a queue runner. It passes on the process id of
the queue runner, together with the file descriptor number of an open
pipe. Closure of the pipe signals the final completion of the sequence
of processes that are passing messages through the same SMTP channel.


File: exim.info,  Node: -MCS,  Next: -MCT,  Prev: -MCQ <process id> <pipe fd>,  Up: Command line options

-MCS _option_
-------------

This option is not intended for use by external callers. It is used
internally by Exim in conjunction with -MC option, and passes on the
fact that the SMTP SIZE option should be used on messages delivered
down the existing channel.


File: exim.info,  Node: -MCT,  Next: -Mc <message id> <message id>,  Prev: -MCS,  Up: Command line options

-MCT _option_
-------------

This option is not intended for use by external callers. It is used
internally by Exim in conjunction with -MC option, and passes on the
fact that the host to which Exim is connected supports TLS encryption.


File: exim.info,  Node: -Mc <message id> <message id>,  Next: -Meb <message id>,  Prev: -MCT,  Up: Command line options

-Mc <message id> <message id> _option_
--------------------------------------

Exim runs a delivery attempt on each message in turn, but unlike the -M
option, it does check for retry hints, and respects any that are found.
This option is not very useful to external callers. It is provided
mainly for internal use by Exim when it needs to re-invoke itself in
order to regain root privilege for a delivery (see chapter "Security
considerations").  However, -Mc can be useful when testing, in order to
run a delivery that respects retry times and other options such as
"hold_domains" that are overridden when -M is used.  Such a delivery
does not count as a queue run. If you want to run a specific delivery
as if in a queue run, you should use -q with a message id argument.  A
distinction between queue run deliveries and other deliveries is made
in one or two places.


File: exim.info,  Node: -Meb <message id>,  Next: -Mes <message id> <address>,  Prev: -Mc <message id> <message id>,  Up: Command line options

-Meb <message id> _option_
--------------------------

This runs, under /bin/sh, the command defined in the shell variable
VISUAL or, if that is not defined, EDITOR or, if that is not defined,
the command "vi", on a copy of the spool file containing the body of
message (`eb' for `edit body'). If the editor exits normally, the
result of editing replaces the spool file. The message is locked during
this process, so no delivery attempts can occur. Note that the first
line of the spool file is its own name; care should be taken not to
disturb this. The thinking behind providing this feature is that an
administrator who has had to mess around with the addresses to get a
message delivered might want to add some comment at the start of the
message text. This option can be used only by an admin user.


File: exim.info,  Node: -Mes <message id> <address>,  Next: -Mf <message id> <message id>,  Prev: -Meb <message id>,  Up: Command line options

-Mes <message id> <address> _option_
------------------------------------

There must be exactly two arguments. The first argument must be a
message id, and the second one an email address. Exim changes the
sender address in the message to the given address, which must be a
fully qualified address or `<>' (`es' for `edit sender'). However, if
the message is active (in the middle of a delivery attempt), its status
is not altered. This option can be used only by an admin user.


File: exim.info,  Node: -Mf <message id> <message id>,  Next: -Mg <message id> <message id>,  Prev: -Mes <message id> <address>,  Up: Command line options

-Mf <message id> <message id> _option_
--------------------------------------

Each listed message is marked `frozen'. This prevents any delivery
attempts taking place until the message is `thawed', either manually or
as a result of the "auto_thaw" configuration option. However, if any of
the messages are active (in the middle of a delivery attempt), their
status is not altered. This option can be used only by an admin user.


File: exim.info,  Node: -Mg <message id> <message id>,  Next: -Mmad <message id> <message id>,  Prev: -Mf <message id> <message id>,  Up: Command line options

-Mg <message id> <message id> _option_
--------------------------------------

Exim gives up trying to deliver the listed messages, including any that
are frozen. A delivery error message is sent, containing the text
`cancelled by administrator'. However, if any of the messages are
active, their status is not altered. This option can be used only by an
admin user.


File: exim.info,  Node: -Mmad <message id> <message id>,  Next: -Mmd <message id> <address> <address>,  Prev: -Mg <message id> <message id>,  Up: Command line options

-Mmad <message id> <message id> _option_
----------------------------------------

Exim marks all the recipient addresses in the messages as already
delivered (`mad' for `mark all delivered'). However, if any message is
active (in the middle of a delivery attempt), its status is not
altered. This option can be used only by an admin user.


File: exim.info,  Node: -Mmd <message id> <address> <address>,  Next: -Mrm <message id> <message id>,  Prev: -Mmad <message id> <message id>,  Up: Command line options

-Mmd <message id> <address> <address> _option_
----------------------------------------------

The first argument must be a message id, and the remaining ones must be
email addresses. Exim marks the given addresses as already delivered
(`md' for `mark delivered'). However, if the message is active (in the
middle of a delivery attempt), its status is not altered. This option
can be used only by an admin user.


File: exim.info,  Node: -Mrm <message id> <message id>,  Next: -Mt <message id> <message id>,  Prev: -Mmd <message id> <address> <address>,  Up: Command line options

-Mrm <message id> <message id> _option_
---------------------------------------

Each message is completely removed from Exim's queue, and forgotten.
However, if any of the messages are active, their status is not
altered. This option can be used only by an admin user or by the user
who originally caused the message to be placed on the queue.


File: exim.info,  Node: -Mt <message id> <message id>,  Next: -Mvb <message id>,  Prev: -Mrm <message id> <message id>,  Up: Command line options

-Mt <message id> <message id> _option_
--------------------------------------

Each of the listed messages that was `frozen' is now `thawed', so that
delivery attempts can resume. However, if any of the messages are
active, their status is not altered. This option can be used only by an
admin user.


File: exim.info,  Node: -Mvb <message id>,  Next: -Mvh <message id>,  Prev: -Mt <message id> <message id>,  Up: Command line options

-Mvb <message id> _option_
--------------------------

The contents of the message body (-D) spool file are written to the
standard output. This option can be used only by an admin user.


File: exim.info,  Node: -Mvh <message id>,  Next: -Mvl <message id>,  Prev: -Mvb <message id>,  Up: Command line options

-Mvh <message id> _option_
--------------------------

The contents of the message headers (-H) spool file are written to the
standard output. This option can be used only by an admin user.


File: exim.info,  Node: -Mvl <message id>,  Next: -m,  Prev: -Mvh <message id>,  Up: Command line options

-Mvl <message id> _option_
--------------------------

The contents of the message log spool file are written to the standard
output.  This option can be used only by an admin user.


File: exim.info,  Node: -m,  Next: -N,  Prev: -Mvl <message id>,  Up: Command line options

-m _option_
-----------

This is apparently a synonym for -om that is accepted by Sendmail, so
Exim treats it that way too.


File: exim.info,  Node: -N,  Next: -n,  Prev: -m,  Up: Command line options

-N _option_
-----------

This is a debugging option that inhibits delivery of a message at the
transport level. It implies at least -d1. Exim goes through many of the
motions of delivery - it just doesn't actually transport the message,
but instead behaves as if it had successfully done so. However, it does
not make any updates to the retry database, and the log entries for
deliveries are flagged with `*>' rather than `=>'.

Because -N discards any message to which it applies, only root or the
Exim user are allowed to use it with -bd, -q, -R or -M. In other words,
an ordinary user can use it only when supplying an incoming message to
which it will apply. Although transportation never fails when -N is
set, an address may be deferred because of a configuration problem on a
transport, or a routing or directing problem. Once -N has been used for
a delivery attempt, it sticks to the message, and applies to any
subsequent delivery attempts that may happen for that message.


File: exim.info,  Node: -n,  Next: -oA <file name>,  Prev: -N,  Up: Command line options

-n _option_
-----------

This option is interpreted by Sendmail to mean `no aliasing'. It is
ignored by Exim.


File: exim.info,  Node: -oA <file name>,  Next: -oB <n>,  Prev: -n,  Up: Command line options

-oA <file name> _option_
------------------------

This option is used by Sendmail in conjunction with -bi to specify an
alternative alias file name. Exim handles -bi differently; see the
description above.


File: exim.info,  Node: -oB <n>,  Next: -odb,  Prev: -oA <file name>,  Up: Command line options

-oB <n> _option_
----------------

This is a debugging option which limits the maximum number of multiple
SMTP deliveries down one channel to <n>, overriding the value set in
the "smtp" transport. If <n> is omitted, the limit is set to 1 (no
batching).


File: exim.info,  Node: -odb,  Next: -odf,  Prev: -oB <n>,  Up: Command line options

-odb _option_
-------------

This option applies to all modes in which Exim accepts incoming
messages, including the listening daemon. It requests `background'
delivery of such messages, which means that the accepting process
automatically starts another delivery process for each message
received. Exim does not wait for such processes to complete (it can
take some time to perform SMTP deliveries). This is the default action
if none of the -od options are present.


File: exim.info,  Node: -odf,  Next: -odi,  Prev: -odb,  Up: Command line options

-odf _option_
-------------

This option (compatible with Smail) requests `foreground' (synchronous)
delivery when Exim has accepted a locally-generated message. (For the
daemon it is exactly the same as -odb.) For a single message received
on the standard input, if the protection regime permits it (see chapter
"Security considerations"), Exim converts the reception process into a
delivery process. In other cases, it creates a new delivery process,
and then waits for it to complete before proceeding.


File: exim.info,  Node: -odi,  Next: -odq,  Prev: -odf,  Up: Command line options

-odi _option_
-------------

This option is synonymous with -odf. It is provided for compatibility
with Sendmail.


File: exim.info,  Node: -odq,  Next: -odqr,  Prev: -odi,  Up: Command line options

-odq _option_
-------------

This option applies to all modes in which Exim accepts incoming
messages, including the listening daemon. It specifies that the
accepting process should not automatically start a delivery attempt for
each message received. Messages are placed on the queue, and remain
there until a subsequent queue-running process encounters them. The
"queue_only" configuration option has the same effect.


File: exim.info,  Node: -odqr,  Next: -odqs,  Prev: -odq,  Up: Command line options

-odqr _option_
--------------

This option applies to all modes in which Exim accepts incoming
messages, including the listening daemon. It causes Exim to process
local addresses when a message is received, but not even to try routing
remote addresses. Contrast with -odqs below, which does the routing,
but not the delivery. The remote addresses will be picked up by the
next queue runner. The "queue_remote_domains" configuration option has
the same effect for specific domains.


File: exim.info,  Node: -odqs,  Next: -oee,  Prev: -odqr,  Up: Command line options

-odqs _option_
--------------

This option is a hybrid between -odb and -odq. A delivery process is
started for each incoming message, the addresses are all processed, and
local deliveries are done in the normal way. However, if any SMTP
deliveries are required, they are not done at this time. Such messages
remain on the queue until a subsequent queue-running process encounters
them. Because routing was done, Exim knows which messages are waiting
for which hosts, and so a number of messages for the same host will get
sent in a single SMTP connection. The "queue_smtp_domains"
configuration option has the same effect for specific domains. See also
the -qq option.


File: exim.info,  Node: -oee,  Next: -oem,  Prev: -odqs,  Up: Command line options

-oee _option_
-------------

If an error is detected while a non-SMTP message is being received (for
example, a malformed address), the error is reported to the sender in a
mail message. Provided the message is successfully sent, Exim exits
with a return code of zero. If not, the return code is 2 if the error
was that the message had no recipients, and 1 otherwise. This is the
default -oex option if Exim is called as "rmail".


File: exim.info,  Node: -oem,  Next: -oep,  Prev: -oee,  Up: Command line options

-oem _option_
-------------

This is the same as -oee, except that Exim always exits with a non-zero
return code, whether or not the error message was successfully sent.
This is the default -oex option, unless Exim is called as "rmail".


File: exim.info,  Node: -oep,  Next: -oeq,  Prev: -oem,  Up: Command line options

-oep _option_
-------------

If an error is detected while a non-SMTP message is being received, the
error is reported by writing a message to the standard error file
(stderr).


File: exim.info,  Node: -oeq,  Next: -oew,  Prev: -oep,  Up: Command line options

-oeq _option_
-------------

This option is supported for compatibility with Sendmail, but has the
same effect as -oep.


File: exim.info,  Node: -oew,  Next: -oi,  Prev: -oeq,  Up: Command line options

-oew _option_
-------------

This option is supported for compatibility with Sendmail, but has the
same effect as -oem.


File: exim.info,  Node: -oi,  Next: -oitrue,  Prev: -oew,  Up: Command line options

-oi _option_
------------

This option, which has the same effect as -i, specifies that a dot on a
line by itself should not terminate an incoming, non-SMTP message.
This is the default if Exim is called as "rmail".


File: exim.info,  Node: -oitrue,  Next: -oMa <host address>,  Prev: -oi,  Up: Command line options

-oitrue _option_
----------------

This option is treated as synonymous with -oi.


File: exim.info,  Node: -oMa <host address>,  Next: -oMas <address>,  Prev: -oitrue,  Up: Command line options

-oMa <host address> _option_
----------------------------

This option sets the sender host address value, and can be used only by
a trusted caller, except in conjunction with the -bh, -bf, -bF, -bt, or
-bv testing options. The host address may include a port number at the
end, after full stop. For example

     exim -bs -oMa 10.9.8.7.1234

A real incoming connection overrides the address set by -oMa. The value
is used in log entries and can appear in "Received:" headers. The
option is intended for use when handing to Exim messages received by
other means, either via the command line or by using the -bs option. If
-oMt is set then -oMa should normally be set as well.


File: exim.info,  Node: -oMas <address>,  Next: -oMai <string>,  Prev: -oMa <host address>,  Up: Command line options

-oMas <address> _option_
------------------------

This option sets the authenticated sender value, and can be used only
by a trusted caller. It overrides the sender address that is created
from the caller's login for messages from local sources. However, it
may be overridden in turn by a message that is received over an
authenticated SMTP connection.  See chapter "SMTP authentication" for
more discussion of authenticated senders.


File: exim.info,  Node: -oMai <string>,  Next: -oMi <interface address>,  Prev: -oMas <address>,  Up: Command line options

-oMai <string> _option_
-----------------------

This option sets the authenticated id value, and can be used only by a
trusted caller. It overrides the default value (the caller's login id)
for messages from local sources. However, it may be overridden in turn
by a successful authentication on an SMTP connection. See chapter "SMTP
authentication" for more discussion of authenticated ids.


File: exim.info,  Node: -oMi <interface address>,  Next: -oMr <protocol name>,  Prev: -oMai <string>,  Up: Command line options

-oMi <interface address> _option_
---------------------------------

This option sets the IP interface address value, and can be used only
by a trusted caller, except in conjunction with the -bh, -bf, -bF, -bt,
or -bv testing options.  A real incoming connection overrides the
address set by -oMi. The option is intended for use when handing to
Exim messages received by other means, either via the command line or
by using the -bs option.


File: exim.info,  Node: -oMr <protocol name>,  Next: -oMs <host name>,  Prev: -oMi <interface address>,  Up: Command line options

-oMr <protocol name> _option_
-----------------------------

This option sets the received protocol value, and can be used only by a
trusted caller, except in conjunction with the -bh, -bf, -bF, -bt, or
-bv testing options.  The value is used in log entries and can appear
in "Received:" headers. The option is intended for use when handing to
Exim messages received by other means. It applies only to non-SMTP and
batched SMTP input.


File: exim.info,  Node: -oMs <host name>,  Next: -oMt <ident string>,  Prev: -oMr <protocol name>,  Up: Command line options

-oMs <host name> _option_
-------------------------

This option sets the sender host name value, and can be used only by a
trusted caller, except in conjunction with the -bh, -bf, -bF, -bt, or
-bv testing options.  The value is used in log entries and can appear
in "Received:" headers. The option is intended for use when handing to
Exim messages received by other means.


File: exim.info,  Node: -oMt <ident string>,  Next: -om,  Prev: -oMs <host name>,  Up: Command line options

-oMt <ident string> _option_
----------------------------

This option sets the sender ident value, and can be used only by a
trusted caller, except in conjunction with the -bh, -bf, -bF, -bt, or
-bv testing options.  The value is used in log entries and can appear
in "Received:" headers. The default setting for local callers is the
login id of the calling process. This can be overridden by supplying an
empty argument. The option is intended for use when handing to Exim
messages received by other means.


File: exim.info,  Node: -om,  Next: -oo,  Prev: -oMt <ident string>,  Up: Command line options

-om _option_
------------

In Sendmail, this option means `me too', indicating that the sender of a
message should receive a copy of the message if the sender appears in
an alias expansion. Exim always does this, so the option does nothing.


File: exim.info,  Node: -oo,  Next: -or <time>,  Prev: -om,  Up: Command line options

-oo _option_
------------

This option is ignored. In Sendmail it specifies `old style headers',
whatever that means.


File: exim.info,  Node: -or <time>,  Next: -ov,  Prev: -oo,  Up: Command line options

-or <time> _option_
-------------------

This option sets a timeout value for incoming non-SMTP messages. If it
is not set, Exim will wait forever for the standard input. The value
can also be set using the "accept_timeout" configuration variable. The
format used for specifying times is described in section "Time
interval" in chapter "The Exim configuration file".


File: exim.info,  Node: -ov,  Next: -oX <number>,  Prev: -or <time>,  Up: Command line options

-ov _option_
------------

This option has exactly the same effect as -v.


File: exim.info,  Node: -oX <number>,  Next: -pd,  Prev: -ov,  Up: Command line options

-oX <number> _option_
---------------------

This option is relevant only when the -bd option is also given. It
overrides any setting of the "daemon_smtp_port" option, and specifies
an alternative TCP/IP port number for the listening daemon.  When used,
the process number of the daemon is written to a file whose name is
"exim-daemon.<number>.pid" in Exim's spool directory or the directory
specified by PID_FILE_PATH in `Local/Makefile'.


File: exim.info,  Node: -pd,  Next: -ps,  Prev: -oX <number>,  Up: Command line options

-pd _option_
------------

This option applies when an embedded Perl interpreter is linked with
Exim (see chapter "Embedded Perl"). It overrides the setting of the
"perl_at_start" option, forcing the starting of the interpreter to be
delayed until it is needed.


File: exim.info,  Node: -ps,  Next: -q,  Prev: -pd,  Up: Command line options

-ps _option_
------------

This option applies when an embedded Perl interpreter is linked with
Exim (see chapter "Embedded Perl"). It overrides the setting of the
"perl_at_start" option, forcing the starting of the interpreter to
occur as soon as Exim is started.


File: exim.info,  Node: -q,  Next: -q <time>,  Prev: -ps,  Up: Command line options

-q _option_
-----------

If the -q option is not followed by a time value, it requests a single
queue run operation. This option requires the caller to be an admin
user. However, there is an option called "prod_requires_admin" which
can be set false to relax this restriction (and also the same
requirement for the -M, -R, and -S options).

Exim starts up a delivery process for each (inactive) message on the
queue in turn, and waits for it to finish before starting the next one.
If the delivery process spawns other processes to deliver other
messages down passed SMTP connections, the queue runner waits for these
to finish before proceeding. When all the queued messages have been
considered, the original process terminates. In other words, a single
pass is made over the waiting mail, one message at a time. Use -q with
a time (see below) if you want this to be repeated periodically.

Exim processes the waiting messages in an unpredictable order. It isn't
very random, but it is likely to be different each time, which is all
that matters.  If one particular message screws up a remote MTA, other
messages to the same MTA have a chance of getting through if they get
tried first.

It is possible to cause the messages to be processed in lexical message
id order, which is essentially the order in which they arrived, by
setting the "queue_run_in_order" option, but this is not recommended
for normal use.

When scanning the queue (either randomly or in order), Exim can be made
to skip over messages whose ids are lexically less than a given value
by following the -q option with a starting message id. For example:

     exim -q 0t5C6f-0000c8-00

Messages that arrived earlier than 0t5C6f-0000c8-00 are not inspected.
If a second message id is given, messages whose ids are lexically
greater than it are also skipped. If the same id is given twice, for
example,

     exim -q 0t5C6f-0000c8-00 0t5C6f-0000c8-00

just one delivery process is started, for that message. This differs
from -M in that retry data is respected, and it also differs from -Mc
in that it counts as a delivery from a queue run. Note that the
selection mechanism does not affect the order in which the messages are
scanned. There are also other ways of selecting specific sets of
messages for delivery in a queue run - see -R and -S.


File: exim.info,  Node: -q <time>,  Next: -qf,  Prev: -q,  Up: Command line options

-q <time> _option_
------------------

This version of the -q option (which again can be run only by an admin
user) causes Exim to run as a daemon, starting a queue-runner process
at intervals specified by the given time value (whose format is
described in section "Time interval" in chapter "The Exim configuration
file"). This form of the -q option is commonly combined with the -bd
option, in which case a single daemon process handles both functions. A
common way of starting up a combined daemon at system boot time is to
use a command such as

     /opt/exim/bin/exim -bd -q30m

Such a daemon listens for incoming SMTP calls, and also fires up a
queue-runner process every 30 minutes. The process id of such a daemon
is written to a file called "exim-daemon.pid" in Exim's spool
directory, unless the -oX option has been used, in which case the file
is called "exim-daemon.<port-number>.pid".  The location of the pid
file can be changed by defining PID_FILE_PATH in `Local/Makefile'. If a
daemon is started without -bd then the -q option used to start it is
added to the pid file name.


File: exim.info,  Node: -qf,  Next: -qff,  Prev: -q <time>,  Up: Command line options

-qf _option_
------------

This option operates like -q, and may appear with or without a following
time. The difference is that a delivery attempt is forced for each
non-frozen message, whereas with -q only those non-frozen addresses
that have passed their retry times are tried.


File: exim.info,  Node: -qff,  Next: -qfl,  Prev: -qf,  Up: Command line options

-qff _option_
-------------

This option operates like -qf and may appear with or without a following
time. The difference is that any frozen messages are automatically
thawed, and delivery is attempted for them.


File: exim.info,  Node: -qfl,  Next: -qffl,  Prev: -qff,  Up: Command line options

-qfl _option_
-------------

This option operates like -ql, and may appear with or without a
following time. The difference is that a delivery attempt is forced for
the local addresses in each non-frozen message, whereas with -ql only
those non-frozen local addresses that have passed their retry times are
tried.


File: exim.info,  Node: -qffl,  Next: -ql,  Prev: -qfl,  Up: Command line options

-qffl _option_
--------------

This option operates like -qfl and may appear with or without a
following time. The difference is that any frozen messages are
automatically thawed, and delivery is attempted for any local addresses
in them.


File: exim.info,  Node: -ql,  Next: -qq,  Prev: -qffl,  Up: Command line options

-ql _option_
------------

This option operates like -q, and may appear with or without a following
time. The difference is that only local addresses (those with domains
that match "local_domains") are considered for delivery. Note that -ql
cannot detect apparently remote addresses that actually turn out to be
local when their domains get fully qualified.


File: exim.info,  Node: -qq,  Next: -qR<flags> <string>,  Prev: -ql,  Up: Command line options

-qq _option_
------------

If any command line option starting with -q is specified with an
additional "q" (for example, -qqf) then all the resulting queue runs
are done in two stages. In the first stage, the queue is scanned as if
the "queue_smtp_domains" option matched every domain.  This causes
remote addresses to be routed, but no transportation to be done.  The
database that remembers which messages are waiting for specific hosts is
updated, as if delivery to those hosts had been deferred. After this is
complete, a second, normal queue scan happens, and normal directing,
routing, and delivery takes place. Messages which are routed to the
same host should mostly be delivered down a single SMTP connection
because of the hints that were set up during the first queue scan.
This option may be useful for hosts that are connected to the Internet
intermittently.


File: exim.info,  Node: -qR<flags> <string>,  Next: -qS<flags> <string>,  Prev: -qq,  Up: Command line options

-qR<flags> <string> _option_
----------------------------

This option is synonymous with -R. It is provided for Sendmail
compatibility.


File: exim.info,  Node: -qS<flags> <string>,  Next: -R<flags> <string>,  Prev: -qR<flags> <string>,  Up: Command line options

-qS<flags> <string> _option_
----------------------------

This option is synonymous with -S.


File: exim.info,  Node: -R<flags> <string>,  Next: -r,  Prev: -qS<flags> <string>,  Up: Command line options

-R<flags> <string> _option_
---------------------------

The <flags> may be empty, in which case the white space before the
string is optional, unless the string is `f', `ff', `r', `rf', or
`rff', which are the possible values for <flags>. White space is
required if <flags> is not empty.

This option is similar to -q with no time value, that is, it causes
Exim to perform a single queue run, except that, when scanning the
messages on the queue, Exim processes only those that have at least one
undelivered address containing the given string, which is checked in a
case-independent way. If the <flags> start with `r', <string> is
interpreted as a regular expression; otherwise it is a literal string.
If the <flags> contain `ff' then frozen messages are included;
otherwise they are omitted.

Once a message is selected, all its addresses are processed. For the
first selected message, Exim overrides any retry information and forces
a delivery attempt for each undelivered address.  This means that if
delivery of any address in the first message is successful, any
existing retry information is deleted, and so delivery attempts for that
address in subsequently selected messages (which are processed without
forcing) will run. However, if delivery of any address does not
succeed, the retry information is updated, and in subsequently selected
messages, the failing address will be skipped.

If the <flags> contain `f' or `ff' then the delivery forcing applies to
all selected messages, not just the first.

The -R option makes it straightforward to initiate delivery of all
messages to a given domain after a host has been down for some time.
When the SMTP command ETRN is permitted (see the "smtp_etrn_hosts"
option), its default effect is to run Exim with the -R option, but it
can be configured to run an arbitrary command instead.


File: exim.info,  Node: -r,  Next: -S<flags> <string>,  Prev: -R<flags> <string>,  Up: Command line options

-r _option_
-----------

This is a documented (for Sendmail) obsolete alternative name for -f.


File: exim.info,  Node: -S<flags> <string>,  Next: -t,  Prev: -r,  Up: Command line options

-S<flags> <string> _option_
---------------------------

This option acts like -R except that it checks the string against each
message's sender instead of against the recipients. If -R is also set,
both conditions must be met for a message to be selected. If either of
the options has `f' or `ff' in its flags, the associated action is
taken.


File: exim.info,  Node: -t,  Next: -U,  Prev: -S<flags> <string>,  Up: Command line options

-t _option_
-----------

When Exim is receiving a locally-generated, non-SMTP message on the
current input, the -t option causes the recipients of the message to be
obtained from the "To:", "Cc:", and "Bcc:" headers in the message
instead of from the command arguments.  The addresses are extracted
before any rewriting takes place.

If there are in fact any arguments, they specify addresses to which the
message is not to be delivered. That is, the argument addresses are
removed from the recipients list obtained from the headers. This is
compatible with Smail 3 and in accordance with the documented behaviour
of several versions of Sendmail, as described in man pages on a number
of operating systems (e.g. Solaris 2.6, IRIX 6.5, HP-UX 11). However,
some versions of Sendmail add argument addresses to those obtained from
the headers, and a 1994 Sendmail book documents it that way.  Exim can
be made to behave in this way by setting the option
"extract_addresses_remove_arguments" false.

If a "Bcc:" header is present, it is removed from the message unless
there is no "To:" or "Cc:" header, in which case a "Bcc:" header with
no data is created, in accordance with RFC 822.


File: exim.info,  Node: -U,  Next: -v,  Prev: -t,  Up: Command line options

-U _option_
-----------

Sendmail uses this option for `initial message submission', and its
documentation states that in future releases, it may complain about
syntactically invalid messages rather than fixing them when this flag
is not set. Exim ignores this option.


File: exim.info,  Node: -v,  Next: -x,  Prev: -U,  Up: Command line options

-v _option_
-----------

This option has exactly the same effect as -d1; it causes Exim to be
`verbose' and produce some output describing what it is doing on the
standard error file. In particular, if an SMTP connection is made, the
SMTP dialogue is shown.


File: exim.info,  Node: -x,  Prev: -v,  Up: Command line options

-x _option_
-----------

AIX uses -x for a private purpose (`mail from a local mail program has
National Language Support extended characters in the body of the mail
item').  It sets -x when calling the MTA from its "mail" command. Exim
ignores this option.


File: exim.info,  Node: File and database lookups,  Next: The Exim configuration file,  Prev: The Exim command line,  Up: Top

File and database lookups
*************************

Exim can be configured to look up data in files or databases in a
number of different circumstances (see "Use of data lookups" below).
Two different styles of data lookup are implemented:

   * The "single-key" style requires the specification of a file in
     which to look, and a single key to search for. The lookup type
     determines how the file is searched.

   * The "query" style accepts a generalized database query, which may
     contain one or more keys.

The code for each lookup type is in a separate source file which is
compiled and included in the binary of Exim only if the corresponding
compile-time option is set. The default settings in `src/EDITME' are:

     LOOKUP_DBM=yes
     LOOKUP_LSEARCH=yes

which means that only linear searching and DBM lookups are included by
default.



* Menu:

* Single-key lookup types::
* An lsearch file is not an item list::
* Query-style lookup types::
* Use of data lookups::
* Temporary errors in lookups::
* Default values in single-key lookups::
* Partial matching in single-key lookups::
* Lookup caching::
* Quoting lookup data::
* More about NIS+::
* More about LDAP::
* More about MySQL and PostgreSQL::
* More about dnsdb::


File: exim.info,  Node: Single-key lookup types,  Next: An lsearch file is not an item list,  Prev: File and database lookups,  Up: File and database lookups

Single-key lookup types
=======================

The following single-key lookup types are implemented:

   * "lsearch": The given file is a text file which is searched
     linearly for a line beginning with the single key, terminated by a
     colon or white space or the end of the line. White space between
     the key and the colon is permitted. The remainder of the line,
     with leading and trailing white space removed, is the data. This
     can be continued onto subsequent lines by starting them with any
     amount of white space, but only a single space character is
     included in the data at such a junction. If the data begins with a
     colon, the key must be terminated by a colon, for example:

          baduser:  :fail:

     Empty lines and lines beginning with # are ignored, even if they
     occur in the middle of an item. This is the traditional textual
     format of alias files.

   * "dbm": Calls to DBM library functions are used to extract data
     from the given DBM file by looking up the record with the given
     key. The terminating binary zero is included in the key that is
     passed to the DBM library.

   * "dbmnz": This is the same as "dbm", except that the terminating
     binary zero is not included in the key that is passed to the DBM
     library. You may need this if you want to look up data in files
     that are created by or shared with some other application that
     does not use terminating zeros. For example, you need to use
     "dbmnz" rather than "dbm" if you want to authenticate incoming
     SMTP calls using the passwords from Courier's
     "/etc/userdbshadow.dat" file. Exim's utility program for creating
     DBM files ("exim_dbmbuild") includes the zeros by default, but has
     an option to omit them (see section "Making DBM files" in chapter
     "Exim utilities").

   * "nis": The given file is the name of a NIS map, and a NIS lookup
     is done with the given key, excluding the terminating binary zero.
     There is a variant called "nis0" which does include the
     terminating binary zero in the key. This is reportedly needed for
     Sun-style alias files. Exim does not recognize NIS aliases; the
     full map names must be used.

   * "cdb": The given file is searched as a Constant DataBase file,
     using the key string without the terminating binary zero. The cdb
     format is designed for indexed files that are read frequently and
     never updated, except by total re-creation. As such, it is
     particulary suitable for large files containing aliases or other
     indexed data referenced by an MTA. Information about cdb can be
     found at

          http://www.pobox.com/~djb/cdb.html

     The cdb distribution is not needed in order to build Exim with cdb
     support, as the code for reading cdb files is included directly in
     Exim itself. However, no means of building or testing cdb files is
     provided with Exim because these are available within the cdb
     distribution.


File: exim.info,  Node: An lsearch file is not an item list,  Next: Query-style lookup types,  Prev: Single-key lookup types,  Up: File and database lookups

An lsearch file is not an item list
===================================

There has been some confusion about the way "lsearch" lookups work, in
particular in domain and host lists. An item in one of these lists may
be a plain file name, or a file name preceded by a search type, and
these behave differently. For a plain file name, for example

     local_domains = /etc/local-mail-domains

each line of the file is treated as if it appeared as an item in the
list, and negated items, wild cards, and regular expressions may be
present. However, if an item is specified as an "lsearch" lookup, for
example

     local_domains = lsearch;/etc/local-mail-domains

then negated items, wild cards, and regular expressions may not be used,
because "lsearch" is an indexed lookup method which, when given a key
(the domain in the above example), yields a data value that corresponds
to that key.  The fact that the file is searched linearly does not make
this kind of search any different from the other single-key lookup
types, and an "lsearch" file can always be directly converted into one
of the other types without change of function. Thus, the keys in
"lsearch"ed files are literal strings and are not interpreted in any
way.


File: exim.info,  Node: Query-style lookup types,  Next: Use of data lookups,  Prev: An lsearch file is not an item list,  Up: File and database lookups

Query-style lookup types
========================

The following query-style lookup types are implemented:

   * "nisplus": This does a NIS+ lookup using a query that may contain
     any number of keys, and which can specify the name of the field to
     be returned. See section "More about NIS+" below.

   * "ldap": This does an LDAP lookup using a query in the form of a
     URL, and returns attributes from a single entry. There is a
     variant called "ldapm" which permits values from multiple entries
     to be returned. A third variant called "ldapdn" returns the
     Distinguished Name of a single entry instead of any attribute
     values.  See section "More about LDAP" below.

   * "mysql": The format of the query is an SQL statement that is
     passed to a MySQL database. See section "More about MySQL and
     PostgreSQL" below.

   * "pgsql": The format of the query is an SQL statement that is
     passed to a PostgreSQL database. See section "More about MySQL and
     PostgreSQL" below.

   * "dnsdb": This does a DNS search for a record whose domain name is
     the supplied query. The resulting data is the contents of the
     record. See section "More about dnsdb" below.

   * "testdb": This is a lookup type which is for use in debugging
     Exim. It is not likely to be useful in normal operation.


File: exim.info,  Node: Use of data lookups,  Next: Temporary errors in lookups,  Prev: Query-style lookup types,  Up: File and database lookups

Use of data lookups
===================

There are three different types of configuration item in which data
lookups can be specified:

  1. Any string that is to be expanded may contain explicit lookup
     requests. String expansions are described in chapter "String
     expansions".

  2. Some drivers can be configured directly to look up data in files.

  3. Lists of domains and other items can contain lookup requests as a
     way of avoiding excessively long linear lists.  In this case, any
     data that is returned by the lookup is normally discarded; whether
     the lookup succeeds or fails is all that counts. However, in the
     case of the "domains" and "local_parts" options for directors and
     routers, the data is preserved in variables for later use. See
     sections "Domain lists" in chapter "The Exim configuration file",
     "Host lists" in chapter "The Exim configuration file", and
     "Address lists" in chapter "The Exim configuration file" for
     descriptions of the different list types.

In a string expansion, all the parameters of the lookup are specified
explicitly, while for the other types there is always one implicit key
involved. For example, the "local_domains" option contains a list of
local domains; when it is being searched there is some domain name that
is an implicit key.

This is not a problem for single-key lookups; the relevant file name is
specified, and the key is implicit. For example, the list of local
domains could be given as

     local_domains = dbm;/local/domain/list

However, for query-style lookups the entire query has to be specified,
and to do this, some means of including the implicit key is required.
The special expansion variable $key is provided for this purpose. NIS+
could be used to look up local domains by a setting such as

     local_domains = nisplus;[domain=$key],domains.org_dir

In cases where drivers can be configured to do lookups, there are
always three alternative configuration options: "file" is used for
single-key lookups, using an implicit key, and "query" or "queries" is
specified for query-style lookups. In these cases the query is an
expanded string, and the implicit key that would be used for "file" is
always available as one of the normal expansion variables. The
difference between "query" and "queries" is that in the latter case the
string is treated as a colon-separated list of queries that are tried
in order until one succeeds.


File: exim.info,  Node: Temporary errors in lookups,  Next: Default values in single-key lookups,  Prev: Use of data lookups,  Up: File and database lookups

Temporary errors in lookups
===========================

Lookup functions can return temporary error codes if the lookup cannot
be completed. (For example, a NIS or LDAP database might be
unavailable.) For this reason, it is not advisable to use a lookup that
might do this for critical options such as (to give an extreme example)
"local_domains".

When a lookup cannot be completed in a transport, director, or router,
delivery of the message is deferred, as for any other temporary error.
In other circumstances Exim may assume the lookup has failed, or may
give up altogether.  These are some specific cases:

   * "local_domains", "hold_domains", or "queue_remote_domains" during
     delivery: the address it is checking is deferred; other addresses
     may succeed if they match something earlier in the list.

   * "domains", "local_parts", "senders", or "condition" on a router or
     director: delivery is deferred.

   * "local_domains", "percent_hack_domains", or "relay_domains" while
     receiving SMTP: a 451 temporary error is given to the RCPT command.

   * "local_domains" during verification: a temporary error given.

   * "mx_domains" during lookuphost: delivery is deferred.

   * "mx_domains" in the smtp transport (for hosts specified on the
     transport): treat as not matching.

   * "queue_smtp_domains" in the smtp transport: treat as not matching -
     otherwise all SMTP deliveries would be held up.


File: exim.info,  Node: Default values in single-key lookups,  Next: Partial matching in single-key lookups,  Prev: Temporary errors in lookups,  Up: File and database lookups

Default values in single-key lookups
====================================

In this context, a `default value' is a value specified by the
administrator that is to be used if a lookup fails.

If `*' is added to a single-key lookup type (for example, "lsearch*")
and the initial lookup fails, the key `*' is looked up in the file to
provide a default value. See also the section on partial matching below.

Alternatively, if `*@' is added to a single-key lookup type (for example
"dbm*@") then, if the initial lookup fails and the key contains an @
character, a second lookup is done with everything before the last @
replaced by *. This makes it possible to provide per-domain defaults in
alias files that include the domains in the keys. If the second lookup
fails (or doesn't take place because there is no @ in the key), `*' is
looked up.


File: exim.info,  Node: Partial matching in single-key lookups,  Next: Lookup caching,  Prev: Default values in single-key lookups,  Up: File and database lookups

Partial matching in single-key lookups
======================================

The normal operation of a single-key lookup is to search the file for
an exact match with the given key. However, in a number of situations
where domains are being looked up, it is useful to be able to do
partial matching. In this case, information in the file that has a key
starting with `*.' is matched by any domain that ends with the
components that follow the full stop. For example, if a key in a DBM
file is

     *.dates.fict.book

then when partial matching is enabled this is matched by (amongst
others) "2001.dates.fict.book" and "1984.dates.fict.book". It is also
matched by "dates.fict.book", if that does not appear as a separate key
in the file.

Partial matching is implemented by doing a series of separate lookups
using keys constructed by modifying the original subject key. This
means that it can be used with any of the single-key lookup types,
provided that the special partial-matching keys beginning with `*.' are
included in the data file. Keys in the file that do not begin with `*.'
are matched only by unmodified subject keys when partial matching is in
use.

Partial matching is requested by adding the string `partial-' to the
front of the name of a single-key lookup type, for example,
"partial-dbm". When this is done, the subject key is first looked up
unmodified; if that fails, `*.'  is added at the start of the subject
key, and it is looked up again. If that fails, further lookups are
tried with dot-separated components removed from the start of the
subject key, one-by-one, and `*.' added on the front of what remains.

A minimum number of two non-* components are required. This can be
adjusted by including a number before the hyphen in the search type.
For example, "partial3-lsearch" specifies a minimum of three non-*
components in the modified keys. Omitting the number is equivalent to
`partial2-'. If the subject key is "2250.dates.fict.book" then the
following keys are looked up when the minimum number of non-*
components is two:

     2250.dates.fict.book
     *.2250.dates.fict.book
     *.dates.fict.book
     *.fict.book

As soon as one key in the sequence is successfully looked up, the lookup
finishes. If `partial0-' is used, the original key gets shortened right
down to the null string, and the final lookup is for `*' on its own.

If the search type ends in `*' or `*@' (see section "Default values in
single-key lookups" above), the search for an ultimate default that
this implies happens after all partial lookups have failed. If
`partial0-' is specified, adding `*' to the search type has no effect,
because the `*' key is already included in the sequence of partial
lookups.

The use of `*' in lookup partial matching differs from its use as a
wildcard in domain lists and the like. Partial matching works only in
terms of dot-separated components; a key such as `*fict.book' in a
database file is useless, because the asterisk in a partial matching
subject key is always followed by a dot.


File: exim.info,  Node: Lookup caching,  Next: Quoting lookup data,  Prev: Partial matching in single-key lookups,  Up: File and database lookups

Lookup caching
==============

Exim caches the most recent lookup result on a per-file basis for
single-key lookup types, and keeps the relevant files open. In some
types of configuration this can lead to many files being kept open for
messages with many recipients.  To avoid hitting the operating system
limit on the number of simultaneously open files, Exim closes the least
recently used file when it needs to open more files than its own
internal limit, which can be changed via the "lookup_open_max" option.
For query-style lookups, a single data cache per lookup type is kept.
The files are closed and the caches flushed at strategic points during
delivery - for example, after all directing and routing is complete.


File: exim.info,  Node: Quoting lookup data,  Next: More about NIS+,  Prev: Lookup caching,  Up: File and database lookups

Quoting lookup data
===================

When data from an incoming message is included in a query-style lookup,
there is the possibility of special characters in the data messing up
the syntax of the query. For example, a NIS+ query that contains

     [name=$local_part]

will be broken if the local part happens to contain a closing square
bracket.  For NIS+, data can be enclosed in double quotes like this:

     [name="$local_part"]

but this still leaves the problem of a double quote in the data. The
rule for NIS+ is that double quotes must be doubled. Other lookup types
have different rules, and to cope with the differing requirements, an
expansion operator of the following form is provided:

     ${quote_<lookup-type>:<string>}

For example, the safest way to write the NIS+ query is

     [name="${quote_nisplus:$local_part}"]

See chapter "String expansions" for full coverage of string expansions.
The quote operator can be used for all lookup types, but has no effect
for single-key lookups, since no quoting is ever needed in their key
strings.


File: exim.info,  Node: More about NIS+,  Next: More about LDAP,  Prev: Quoting lookup data,  Up: File and database lookups

More about NIS+
===============

NIS+ queries consist of a NIS+ "indexed name" followed by an optional
colon and field name. If this is given, the result of a successful
query is the contents of the named field; otherwise the result consists
of a concatenation of "field-name=field-value" pairs, separated by
spaces. Empty values and values containing spaces are quoted. For
example, the query

     [name=mg1456],passwd.org_dir

might return the string

     name=mg1456 passwd="" uid=999 gid=999 gcos="Martin Guerre"
     home=/home/mg1456 shell=/bin/bash shadow=""

(split over two lines here to fit on the page), whereas

     [name=mg1456],passwd.org_dir:gcos

would just return

     Martin Guerre

with no quotes. A NIS+ lookup fails if NIS+ returns more than one table
entry for the given indexed key.  The effect of the "quote_nisplus"
expansion operator is to double any quote characters within the text.


File: exim.info,  Node: More about LDAP,  Next: More about MySQL and PostgreSQL,  Prev: More about NIS+,  Up: File and database lookups

More about LDAP
===============

The original LDAP implementation came from the University of Michigan;
this has become `Open LDAP', and there are now two different releases.
Another implementation comes from Netscape, and Solaris 7 and
subsequent releases contain inbuilt LDAP support. Unfortunately, though
these are all compatible at the lookup function level, their error
handling is different. For this reason it is necessary to set a
compile-time variable when building Exim with LDAP, to indicate which
LDAP library is in use. One of the following should appear in your
`Local/Makefile':

     LDAP_LIB_TYPE=UMICHIGAN
     LDAP_LIB_TYPE=OPENLDAP1
     LDAP_LIB_TYPE=OPENLDAP2
     LDAP_LIB_TYPE=NETSCAPE
     LDAP_LIB_TYPE=SOLARIS

If LDAP_LIB_TYPE is not set, Exim assumes OpenLDAP 1, which has the same
interface as the University of Michigan version.

There are three LDAP lookup types, which behave slightly differently in
the way they handle the results of a query.

   * "ldap" requires the result to contain just one entry; if there are
     more, it gives an error.

   * "ldapdn" also requires the result to contain just one entry, but
     it is the Distinguished Name that is returned rather than any
     attribute values.

   * "ldapm" permits the result to contain more than one entry; the
     attributes from all of them are returned.

An LDAP query takes the form of a URL as defined in RFC 2255. For
example, in the configuration of an "aliasfile" director one might have
these settings:

     search_type = ldap
     query = ldap:///cn=$local_part,o=University%20of%20Cambridge,\
             c=UK?mailbox?base?

Two levels of quoting are required in LDAP queries, the first for LDAP
and the second because the LDAP query is represented as a URL. The
"quote_ldap" expansion operator implements the following rules:

   * For LDAP quoting, the characters #,+"\<>;*() have to be preceded
     by a backslash. (In fact, only some of these need to be quoted in
     Distinguished Names, and others in LDAP filters, but it does no
     harm to have a single quoting rule for all of them.)

   * For URL quoting, all characters except alphanumerics and
     !$'()*+-._ are replaced by %xx where xx is the hexadecimal
     character code. Note that backslash has to be quoted in a URL, so
     characters that are escaped for LDAP end up preceded by %5C in the
     final encoding.

The example above does not specify an LDAP server. A server can be
specified in a query by starting it with

     ldap://<hostname>:<port>/...

If the port (and preceding colon) are omitted, the standard LDAP port
(389) is used. When, however, no server is specified in a query, a list
of default servers is taken from the "ldap_default_servers"
configuration option. This supplies a colon-separated list of servers
which are tried in turn until one successfully handles a query, or
there is a serious error. Successful handling either returns the
requested data, or indicates that it does not exist. Serious errors are
syntactical, or multiple values when only a single value is expected.
Errors which cause the next server to be tried are connection failures,
bind failures, and timeouts.

For each server name in the list, a port number can be given. The
standard way of specifing a host and port is to use a colon separator
(RFC 1738). Because "ldap_default_servers" is a colon-separated list,
such colons have to be doubled. For example

     ldap_default_servers = ldap1.example.com::145:ldap2.example.com

If "ldap_default_servers" is unset, a URL with no server name is passed
to the LDAP library with no server name, and the library's default
(normally the local host) is used.

The LDP URL syntax provides no way of passing authentication and other
control information to the server. To make this possible, the URL in an
LDAP query may be preceded by any number of `<name>=<value>' settings,
separated by spaces. If a value contains spaces it must be enclosed in
double quotes, and when double quotes are used, backslash is
interpreted in the usual way inside them. The following names are
recognized:

     USER     set the DN, for authenticating the LDAP bind
     PASS     set the password, likewise
     SIZE     set the limit for the number of entries returned
     TIME     set the maximum waiting time for a query

The values may be given in any order.  The default is no time limit,
and no limit on the number of entries returned.  Here is an example of
an LDAP query in an Exim lookup which uses some of these values. This
is a single line, folded for ease of reading:

     ${lookup ldap
       {user="cn=manager,o=University of Cambridge,c=UK" pass=secret
       ldap:///o=University%20of%20Cambridge,c=UK?sn?sub?(cn=foo)}
       {$value}fail}

The encoding of spaces as %20 is a URL thing which should not be done
for any of the auxiliary data.  Exim configuration settings that
include lookups which contain password information should be preceded
by `hide' to prevent non-admin users from using the -bP option to see
their values.

The "ldapdn" lookup type returns the Distinguished Name from a single
entry as a sequence of values, for example

     cn=manager, o=University of Cambridge, c=UK

For "ldap" and "ldapm", if a query finds only entries with no
attributes, Exim behaves as if the entry did not exist, and the lookup
fails.

The "ldap" lookup type generates an error if more than one entry
matches the search filter, whereas "ldapm" permits this case, and
inserts a newline in the result between the data from different
entries. It is possible for multiple values to be returned for both
"ldap" and "ldapm", but in the former case you know that whatever
values are returned all came from a single entry in the directory.

In the common case where you specify a single attribute in your LDAP
query, the result is not quoted, and if there are multiple values, they
are separated by commas. If you specify multiple attributes, they are
returned as space-separated strings, quoted if necessary, preceded by
the attribute name.  For example,

     ldap:///o=base?attr1,attr2?sub?(uid=fred)

might yield

     attr1="value one" attr2=value2

If you do not specify any attributes in the search, the same format is
used for all attributes in the entry. For example,

     ldap:///o=base??sub?(uid=fred)

might yield

     objectClass=top attr1="value one" attr2=value2

The "extract" operator in string expansions can be used to pick out
individual fields from such data.


File: exim.info,  Node: More about MySQL and PostgreSQL,  Next: More about dnsdb,  Prev: More about LDAP,  Up: File and database lookups

More about MySQL and PostgreSQL
===============================

If any MySQL or PostgreSQL lookups are used, the "mysql_servers" or
"pgsql_servers" option (as appropriate) must be set to a colon-separated
list of slash-separated host, database, user, password, tuples. Because
password data is sensitive, you should precede the setting with `hide',
to prevent non-admin users from obtaining the setting via the -bP
option. For example:

     hide mysql_servers = localhost/users/root/secret:\
                          otherhost/users/root/othersecret

For MySQL, an empty server name causes a connection to the server on
the local host by means of a Unix domain socket.

For each query, these parameter groups are tried in order until a
connection and a query succeeds. For MySQL, no database need be
supplied - if it is absent, it must be given in the queries. A host may
be specified as <name>:<port> but because this is a colon-separated
list, the colon has to be doubled. Queries are SQL statements, so an
example might be

     ${lookup mysql{select mailbox from users where id='ph10'}{$value}fail}

If the result of the query contains more than one field, the data for
each field in the row is returned, preceded by its name, so the result
of

     ${lookup pgsql{select home,name from users where id='ph10'}{$value}}

might be

     home=/home/ph10 name="Philip Hazel"

Values containing spaces and empty values are double quoted, with
embedded quotes escaped by a backslash.

If the result of the query contains just one field, the value is passed
back verbatim, without a field name, for example:

     Philip Hazel

If the result of the query yields more than one row, it is all
concatenated, with a newline between the data for each row.

The "quote_mysql" and "quote_pgsql" expansion operators convert
newline, tab, carriage return, and backspace to \n, \t, \r, and \b
respectively, and the characters single-quote, double-quote, and
backslash are escaped with backslashes. The "quote_pgsql" expansion
operator, in addition, escapes the percent and underscore characters.
This cannot be done for MySQL because these escapes are not recognized
in contexts where these characters are not special.


File: exim.info,  Node: More about dnsdb,  Prev: More about MySQL and PostgreSQL,  Up: File and database lookups

More about dnsdb
================

The "dnsdb" lookup type uses the DNS as its database. A query consists
of a record type and a domain name, separated by an equals sign. For
example, an expansion string could contain:

     ${lookup dnsdb{mx=a.b.example}{$value}fail}

The supported record types are A, CNAME, MX, NS, PTR, and TXT, and,
when Exim is compiled with IPv6 support, AAAA and A6. If no type is
given, TXT is assumed. When the type is PTR, the address should be
given as normal; it gets converted to the necessary inverted format
internally. For example:

     ${lookup dnsdb{ptr=192.168.4.5}{$value}fail}

For MX records, both the preference value and the host name are
returned, separated by a space. If multiple records are found (or, for
A6 lookups, if a single record leads to multiple addresses), the data
is returned as a concatenation, separated by newlines. The order, of
course, depends on the DNS resolver.


File: exim.info,  Node: The Exim configuration file,  Next: Regular expressions,  Prev: File and database lookups,  Up: Top

The Exim configuration file
***************************

Exim uses a single run time configuration file which is read whenever
an Exim binary is executed.  The name of the file is compiled into the
binary for security reasons, and is specified by the CONFIGURE_FILE
compilation option.

Some sites may wish to use the same Exim binary on different machines
that share a file system, but to use different configuration files on
each machine. If CONFIGURE_FILE_USE_NODE is defined in `Local/Makefile',
Exim first looks for a file whose name is the configuration file name
followed by a dot and the machine's node name, as obtained from the
"uname()" function.  If this file does not exist, the standard name is
tried.

In some esoteric situations different versions of Exim may be run under
different effective uids and the CONFIGURE_FILE_USE_EUID is defined to
help with this. See the comments in `src/EDITME' for details.

The run time configuration file must be owned by root or by the user
that is specified at compile time by the EXIM_UID option, and it must
not be world-writeable or group-writeable, unless its group is the one
specified at compile time by the EXIM_GID option.

Macros in the configuration file can be overridden by the -D command
line option, and a one-off alternative configuration file can be
specified by the -C command line option, but if either of these options
are used, Exim immediately gives up its root privilege, unless called
by root or the Exim user. -C is useful mainly for checking the syntax
of configuration files before installing them. No owner or group checks
are done on a configuration file specified by -C.

A default configuration file, which will work correctly in simple
situations, is provided in the file "src/configure.default". The
installation process copies this into CONFIGURE_FILE if there is no
previously-existing configuration file.

If a syntax error is detected while reading the configuration file, Exim
writes a message on the standard error, and exists with a non-zero
return code.  The message is also written to the panic log.



* Menu:

* Configuration file format::
* Macros in the configuration file::
* Common option syntax::
* Integer::
* Octal integer::
* Fixed point number::
* Time interval::
* String::
* Expanded strings::
* User and group names::
* List construction::
* Domain lists::
* Host lists::
* Mixing host names and addresses in host lists::
* Use of RFC 1413 identification in host lists::
* Address lists::
* Case of letters in address lists::


File: exim.info,  Node: Configuration file format,  Next: Macros in the configuration file,  Prev: The Exim configuration file,  Up: The Exim configuration file

Configuration file format
=========================

Exim's configuration file is in seven parts, which must appear in the
correct order in the file, separated by lines containing just the word
`end'. However, any parts at the end of the file that are not required
may be omitted. The file contains:

   * Main configuration settings: options for controlling input, and
     other overall parameters that are not specific to any of the
     drivers.

   * Configuration settings for the transport drivers. Transports
     define mechanisms for copying messages to destinations.

   * Configuration settings for the director drivers. Directors process
     local addresses, that is, those with domains that match
     "local_domains". These are typically (but not necessarily)
     delivered on the local host.

   * Configuration settings for the router drivers. Routers process
     remote addresses, that is, those with domains that do not match
     "local_domains".

   * Retry rules, for use when a message cannot be immediately
     delivered.

   * Address rewriting rules, for use when a message arrives and when
     new addresses are generated during delivery.

   * Configuration settings for the authenticator drivers. These are
     concerned with the SMTP AUTH command (see chapter "SMTP
     authentication"), and this part of the configuration can be
     omitted when AUTH is not in use.

Blank lines in the file, and lines starting with a # character (ignoring
leading white space) are treated as comments and are ignored. Note that
a # character other than at the beginning of a line is not treated
specially, and does not introduce a comment.

Any non-comment line can be continued by ending it with a backslash.
Trailing white space after the backslash is ignored, and leading white
space at the start of continuation lines is also ignored. Comment lines
may appear in the middle of a sequence of continuation lines.

A convenient way to create a configuration file is to start from the
default, which is supplied in "src/configure.default", and add, delete,
or change settings as required.

The retry and rewriting rules have their own syntax which is described
in chapters "Retry configuration" and "Address rewriting",
respectively. The other parts of the configuration file (whose settings
are described in chapters "Main configuration"-"The queryprogram
router" and "SMTP authentication"-"The cram_md5 authenticator") have
some syntactic items in common, and these are described below, from
section "Common option syntax" onwards. Before that, the simple macro
facility is introduced.


File: exim.info,  Node: Macros in the configuration file,  Next: Common option syntax,  Prev: Configuration file format,  Up: The Exim configuration file

Macros in the configuration file
================================

If a line in the main part of the configuration (that is, before the
first `end' line) begins with an upper-case letter, it is taken as a
macro definition, and must be of the form

     <name> = <rest of line>

The name must consist of letters, digits, and underscores, and need not
all be in upper-case, though that is recommended.  The rest of the
line, including any continuations, is the replacement text, and has
leading and trailing white space removed. Quotes are not removed. The
replacement text can never end with a backslash character, but this
doesn't seem to be a serious limitation.

Once a macro is defined, all subsequent lines in the file are scanned
for the macro name; if there are several macros, the line is scanned
for each in turn, in the order in which they are defined. The
replacement text is not re-scanned for the current macro, though it
will be for subsequently defined macros.  For this reason, a macro name
may not contain the name of a previously defined macro as a substring.
You could, for example, define

     ABCD_XYZ = <<something>>
     ABCD = <<something>>

but putting the definitions in the opposite order would provoke a
configuration error.

As an example of macro usage, suppose you have lots of local domains,
but they fall into three different categories. You could set up

     LOCAL1 = domain1:\
              domain2
     LOCAL2 = domain3:domain4
     LOCAL3 = dbm;/list/of/other/domains
     
     local_domains = LOCAL1:LOCAL2:LOCAL3

and then use the "domains" option on appropriate directors to handle
each set of domains differently. This avoids having to list each domain
in more than one place.  Warning: This technique is convenient only for
positive lists. Because it is just a textual replacement, preceding a
macro name in a list with ! has the effect of negating just the first
item within the macro, not all of them.


File: exim.info,  Node: Common option syntax,  Next: Integer,  Prev: Macros in the configuration file,  Up: The Exim configuration file

Common option syntax
====================

For the main set of options and for driver options, each setting is on a
line by itself, and starts with a name consisting of lower-case letters
and underscores. Many options require a data value, and in these cases
the name must be followed by an equals sign (with optional white space)
and then the value.  For example:

     qualify_domain = mydomain.example.com

Some option settings may contain sensitive data, for example, passwords
for accessing databases. To stop non-admin users from using the -bP
command line option to read their values, you can precede them with the
word `hide'. For example:

     hide mysql_servers = localhost/users/admin/secret-password

For non-admin users, such options are displayed like this:

     mysql_servers = <value not displayable>

If `hide' is used on a driver option, it hides the value of that option
on all instances of the same driver.

Options whose type is given as boolean are on/off switches that are not
always followed by a data value. If the option name is specified on its
own without data, the switch is turned on; if it is preceded by `no_' or
`not_' the switch is turned off. However, boolean options may be
followed by an equals sign and one of the words `true', `false', `yes',
or `no'. For example:

     sender_verify
     no_smtp_verify
     queue_only = true

The types of data that are used by non-boolean options are described in
the following sections.


File: exim.info,  Node: Integer,  Next: Octal integer,  Prev: Common option syntax,  Up: The Exim configuration file

Integer
=======

If a numerical data item starts with the characters `0x', the remainder
of it is interpreted as a hexadecimal number. Otherwise, it is treated
as octal if it starts with the digit 0, and decimal if not. If an
integer value is followed by the letter K, it is multiplied by 1024; if
it is followed by the letter M, it is multiplied by 1024x1024.

When the values of integer option settings are output, values which are
an exact multiple of 1024 or 1024x1024 are printed using the letters K
and M. The printing style is independent of the actual input format
that was used.


File: exim.info,  Node: Octal integer,  Next: Fixed point number,  Prev: Integer,  Up: The Exim configuration file

Octal integer
=============

The value of an option specified as an octal integer is always
interpreted in octal, whether or not it starts with the digit zero.
Such options are always output in octal.


File: exim.info,  Node: Fixed point number,  Next: Time interval,  Prev: Octal integer,  Up: The Exim configuration file

Fixed point number
==================

A fixed point number consists of a decimal integer, optionally followed
by a decimal point and up to three further digits.


File: exim.info,  Node: Time interval,  Next: String,  Prev: Fixed point number,  Up: The Exim configuration file

Time interval
=============

A time interval is specified as a sequence of numbers, each followed by
one of the following letters, with no intervening white space:

     "s"    seconds
     "m"    minutes
     "h"    hours
     "d"    days
     "w"    weeks

For example, `3h50m' specifies 3 hours and 50 minutes. The values of
time intervals are output in the same format.


File: exim.info,  Node: String,  Next: Expanded strings,  Prev: Time interval,  Up: The Exim configuration file

String
======

If a string data item does not start with a double-quote character, it
is taken as consisting of the remainder of the line plus any
continuation lines, starting at the first character after any white
space, with trailing white space characters removed, and with no
interpretation of the characters therein. Because Exim removes comment
lines (those beginning with #) at an early stage, they can appear in
the middle of a multi-line string. The following settings are therefore
equivalent:

     trusted_users = uucp:mail
     
     trusted_users = uucp:\
                     # This comment line is ignored
                     mail

If a string does start with a double-quote, it must end with a closing
double-quote, and any backslash characters other than those used for
line continuation are interpreted as escape characters, as follows:

     \\               single backslash
     \n               newline
     \r               carriage return
     \t               tab
     \<octal digits>  up to 3 octal digits specify one character
     \x<hex digits>   up to 2 hexadecimal digits specify one character

If a backslash is followed by some other character, including a
double-quote character, that character replaces the pair.

Quoting is necessary only if you want to make use of the backslash
escapes to insert special characters, or if you need to specify a value
with leading or trailing spaces. However, in versions of Exim before
3.14, quoting was required in order to continue lines, so you may come
across older configuration files and examples that apparently quote
unnecessarily.


File: exim.info,  Node: Expanded strings,  Next: User and group names,  Prev: String,  Up: The Exim configuration file

Expanded strings
================

Some strings in the configuration file are subjected to "string
expansion", by which means various parts of the string may be changed
according to the circumstances (see chapter "String expansions"). The
input syntax for such strings is as just described; in particular, the
handling of backslashes in quoted strings is done as part of the input
process, before expansion takes place. However, backslash is also an
escape character for the expander, so any backslashes that are required
for that reason must be doubled if they are within a quoted
configuration string.


File: exim.info,  Node: User and group names,  Next: List construction,  Prev: Expanded strings,  Up: The Exim configuration file

User and group names
====================

User and group names are specified as strings, using the syntax
described above, but the strings are interpreted specially. In the main
section of the configuration file, a user or group name must either
consist entirely of digits, or be a name that can be looked up using
the "getpwnam()" or "getgrnam()" function, as appropriate.

When a user or group is specified as an option for a driver, it may
alternatively be a string that gets expanded each time the user or
group value is required. The presence of a "$" character in the string
causes this action to happen. Each time the string is expanded, the
result must either be a digit string, or a name that can be looked up
using "getpwnam()" or "getgrnam()", as appropriate.


File: exim.info,  Node: List construction,  Next: Domain lists,  Prev: User and group names,  Up: The Exim configuration file

List construction
=================

Some configuration settings accept a colon-separated list of items. In
these cases, the entire list is treated as a single string as far as
the input syntax is concerned. The "trusted_users" setting in section
"String" above is an example. If a colon is actually needed in an item
in a list, it must be entered as two colons. Leading and trailing white
space on each item in a list is ignored. This makes it possible to
include items that start with a colon, and in particular, certain forms
of IPv6 address. For example, the list

     local_interfaces = 127.0.0.1 : ::::1

contains two IP addresses, the IPv4 address 127.0.0.1 and the IPv6
address ::1.  IPv6 addresses are going to become more and more common
as the new protocol gets more widely deployed.  Doubling their colons
is an unwelcome chore, so a mechanism was introduced to allow the
separator character to be changed. If a list begins with a left angle
bracket, followed by any punctuation character, that character is used
instead of colon as the list separator. For example, the list above can
be rewritten to use a semicolon separator like this:

     local_interfaces = <; 127.0.0.1 ; ::1

This facility applies to all lists, with the exception of the lists in
"log_file_path" and "tls_verify_ciphers". It is recommended that the
use of non-colon separators be confined to circumstances where they
really are needed.


File: exim.info,  Node: Domain lists,  Next: Host lists,  Prev: List construction,  Up: The Exim configuration file

Domain lists
============

Domain lists are constructed as described in section "List
construction". They contain patterns that are to be matched against a
mail domain. For example, the "local_domains" option is a domain list,
one of whose patterns must match every domain that Exim is to treat as
local.

Items in a domain list may be positive or negative. Negative items are
indicated by a leading exclamation mark, which may be followed by
optional white space. The list is scanned from left to right. If the
domain matches a positive item, it is in the set of domains which the
list defines; if it matches a negative item, it is not in the set. If
the end of the list is reached without the domain having matched any of
the patterns, it is accepted if the last item was a negative one, but
not if it was a positive one. For example,

     relay_domains = !a.b.c : *.b.c

matches any domain ending in `.b.c' except for `a.b.c'. Domains that
match neither `a.b.c' nor `*.b.c' are not accepted, because the last
item in the list is positive. However, if the setting were

     relay_domains = !a.b.c

then all domains other than `a.b.c' would be accepted because the last
item in the list is negative. In effect, a list that ends with a
negative item behaves as if it had `: *' appended to it.

The following types of item may appear in domain lists:

   * If an item in a domain list is a plain absolute file name
     (beginning with a slash character), each line of the file is read
     and processed as if it were an independent item in the list,
     except that further plain file names are not allowed. This happens
     each time the list is searched. If a # character appears anywhere
     in a line of the file, it and all following characters are ignored.
     Blank lines are also ignored. Wild cards, negation, and regular
     expressions may be used in the lines of the file, just as in the
     main list. For example, if

          local_domains = /etc/local-domains

     then the file could contain lines like

          ^.*\d{3}\.mydomain\.com$

     If a plain file name is preceded by an exclamation mark, the sense
     of any match within the file is inverted. For example, if

          hold_domains = !/etc/nohold-domains

     and the file contains the lines

          !a.b.c
          *.b.c

     then `a.b.c' is in the set of domains defined by "hold_domains",
     whereas any domain matching `*.b.c' is not.

   * If a pattern consists of a single @ character, it matches the
     local host name, as set in the "primary_hostname" option. This
     makes it possible to use the same configuration file on several
     different hosts that differ only in their names.

   * If a pattern starts with an asterisk, the remaining characters of
     the pattern are compared with the terminating characters of the
     domain. The use of `*' in domain lists differs from its use in
     partial matching lookups. In a domain list, the character
     following the asterisk need not be a dot, whereas partial matching
     works only in terms of dot-separated components. For example, a
     domain list item such as `*key.ex' matches `donkey.ex' as well as
     `cipher.key.ex'.

   * If a pattern starts with a circumflex character, it is treated as a
     regular expression, and matched against the domain using a regular
     expression matching function. The circumflex is treated as part of
     the regular expression.  References to descriptions of the syntax
     of regular expressions are given in chapter "Regular expressions",
     but note that if a backslash is required in the regular
     expression, it must be given as two backslashes if the string is
     in quotes.

     There are some cases where a domain list is the result of string
     expansion, for example the "domains" option in routers and
     directors. In these cases you must escape any backslash and dollar
     characters in regular expressions, to prevent them from being
     interpreted by the string expander, and if the string is specified
     in quotes, the resulting backslashes must themselves also be
     escaped.

   * If a pattern starts with the name of a single-key lookup type
     followed by a semicolon (for example, `dbm;' or `lsearch;') then
     the remainder of the pattern must be a file name in a suitable
     format for the lookup type. For example, for `cdb;' it must be an
     absolute path:

          local_domains = cdb;/etc/mail/local_domains.cdb

     The appropriate type of lookup is done on the file using the
     domain name as the key. In most cases, the data that is looked up
     is not used; Exim is interested only in whether or not the key is
     present in the file. However, when a lookup is used for the
     "domains" option on a director or router, the data is preserved in
     the $domain_data variable and can be referred to in other options.

     Note that this type of entry is not an `include' facility when the
     lookup type is `lsearch'. The keys in the file are not interpreted
     specially, as they would be if they appeared as individual items
     in the domain list, or as lines in a file referenced without a
     search type.

   * Any of the single-key lookup type names may be preceded by
     `partial<n>-', where the <n> is optional, for example,

          partial-dbm;/partial/domains

     This causes partial matching logic to be invoked; a description of
     how this works is given in section "Partial matching in single-key
     lookups" in chapter "File and database lookups".

   * Any of the single-key lookup types may be followed by an asterisk.
     This causes a default lookup for a key consisting of a single
     asterisk to be done if the original lookup fails. This is not a
     useful feature when using a domain list to select particular
     domains (because any domain would match), but it might have value
     if the result of the lookup is being used via the $domain_data
     expansion variable.

   * If the pattern starts with the name of a query-style lookup type
     followed by a semicolon (for example, `nisplus;' or `ldap;'), the
     remainder of the pattern must be an appropriate query for the
     lookup type, as described in chapter "File and database lookups".
     The query is expanded before use, and the expansion substitution
     $key can be used to insert the domain that is being tested into
     the query.  For example:

          local_domains = mysql;select domain from domainlist \
            where domain = '$key';

     In most cases, the data that is looked up is not used (so for an
     SQL query, for example, it doesn't matter what field you select).
     Exim is interested only in whether or not the key is present in
     the file. However, when a lookup is used for the "domains" option
     on a director or router, the data is preserved in the $domain_data
     variable and can be referred to in other options.

   * If none of the above cases apply, a caseless textual comparison is
     made between the pattern and the domain.

Here is an example which uses several different kinds of pattern:

     local_domains = @:\
                     lib.unseen.edu:\
                     *.foundation.fict.book:\
                     ^[1-2]\d{3}\.fict\.book$:\
                     partial-dbm;/opt/data/penguin/book:\
                     nis;domains.byname:\
                     nisplus;[name=$key,status=local],domains.org_dir

There are obvious processing trade-offs among the various matching
modes. Using an asterisk is faster than a regular expression, and
listing a few names explicitly probably is too. The use of a file or
database lookup is expensive, but may be the only option if hundreds of
names are required. Because the patterns are tested in order, it makes
sense to put the most commonly matched patterns earlier.


File: exim.info,  Node: Host lists,  Next: Mixing host names and addresses in host lists,  Prev: Domain lists,  Up: The Exim configuration file

Host lists
==========

Host lists are constructed as described in section "List construction".
They contain patterns which are matched against host names or IP
addresses. Host lists are used to control what remote hosts are allowed
to do (for example, use the local host as a relay). Their patterns
define a set of hosts that the list matches.

Items in the list may be positive or negative. Negation is indicated by
preceding an item with an exclamation mark. A plain absolute file name
(beginning with a slash) can be used to include items from a file.
Negation and included files operate exactly as for domain lists - see
section "Domain lists" for examples.

The following types of pattern may appear in a host list:

   * If the entire item is `*' it matches any host.

   * If the item is in the form of an IP address, it is matched against
     the IP address of the subject host. The presence of a colon is
     taken as an indication that it is an IPv6 address (when IPv6
     support is compiled into Exim); such colons have to be doubled
     when colon is the item separator in the list (the default).

   * If the item is in the form of an IP address followed by a slash
     and a mask length (for example 10.11.0.0/16) then it is matched
     against the IP address of the subject host under the given mask,
     which specifies the number of address bits that must match,
     starting from the most significant end. Thus an entire network of
     hosts can be included (or excluded) by a single item.

     IPv4 addresses are given in the normal `dotted-quad' notation.
     IPv6 addresses are given in colon-separated format, but the colons
     have to be doubled so as not to be taken as item separators. This
     example shows both kinds of address:

          receiver_unqualified_hosts = 172.16.0.0/12: \
                                       5f03::1200::836f::::/48

     The doubling of list separator characters applies only when such
     addresses appear inline in a host list. It is not required when
     indirecting via a file.  For example,

          receiver_unqualified_hosts = /opt/exim/unqualnets

     could make use of a file containing

          172.16.0.0/12
          5f03:1200:836f::/48

     to have exactly the same effect as the previous example.  When
     listing small numbers of IPv6 addresses inline, is is usually more
     convenient to use the facility for changing separator characters.
     This list contains the same two addresses:

          receiver_unqualified_hosts = <; 172.16.0.0/12; \
                                          5f03:1200:836f::/48

     If an IPv4 host calls an IPv6 host, the incoming address actually
     appears in the IPv6 host as `::ffff:<v4address>'. When such an
     address is tested against a  host list, it is converted into a
     traditional IPv4 address first.

   * If the item is of the form

          net<number>-<search-type>;<search-data>

     for example:

          net24-dbm;/networks.db

     then the IP address of the subject host is masked using <number>
     as the mask length; a textual string is then constructed from the
     masked value, followed by the mask, and this is then used as the
     key for the lookup. For example, if the host's IP address is
     192.168.34.6 then the key that is looked up for the above example
     is `192.168.34.0/24'. IPv6 addresses are converted to a text value
     using lower case letters and full stops (periods) as separators
     instead of the more usual colon, because colon is the key
     terminator in "lsearch" files. Full, unabbreviated IPv6 addresses
     are always used.

   * If the item is of the form

          net-<search-type>;<search-data>

     then the text form of the IP address of the subject host is used
     unmasked as the lookup key. This is not the same as specifying
     "net32" for an IPv4 address or "net128" for an IPv6 address,
     because the mask value is not included in the key. However, IPv6
     addresses are still converted to an unabbreviated form, using
     lower case letters and full stops as separators.

   * If the entire item is `@' the primary host name is used as the
     match item, and the following applies:

   * If the item is a plain domain name, Exim calls "gethostbyname()"
     to find its IP address(es). This typically causes a forward DNS
     lookup of the name. The result is compared with the IP address of
     the subject host.

The remaining items are wildcarded patterns for matching against the
host name.  If the host name is not already known, Exim calls
"gethostbyaddr()" to obtain it from the IP address. This typically
causes a reverse DNS lookup to occur. If the lookup fails, Exim takes a
hard line by default and access is not permitted. If the list is an
`accept' list, Exim behaves as if the current host is not in the set
defined by the list, whereas if it is a `reject' list, it behaves as if
it is.

To change this behaviour, the special item `+allow_unknown' may appear
in the list (at top level - it is not recognized in an indirected
file). If any subsequent items require a host name, and the reverse DNS
lookup fails, Exim permits the access, that is, its behaviour is the
opposite to the default. For example,

     host_reject = +allow_unknown:*.enemy.ex

rejects connections from any host whose name matches `*.enemy.ex', but
only if it can find a host name from the incoming IP address.  If
`+warn_unknown' is used instead of `+allow_unknown', the effect is the
same, except that Exim writes an entry to its log when it accepts a
host whose name it cannot look up.

As a result of aliasing, hosts may have more than one name. When
processing any of the following items, all the host's names are checked.

   * If the item starts with `*' then the remainder of the item must
     match the end of the host name. For example, `*.b.c' matches all
     hosts whose names end in `.b.c'. This special simple form is
     provided because this is a very common requirement. Other kinds of
     wildcarding require the use of a regular expression.

   * If the item starts with `^' then it is taken to be a regular
     expression which is matched against the host name. For example,

          ^(a|b)\.c\.d$

     matches either of the two hosts "a.c.d" or "b.c.d". If the option
     string in which this occurs is given in quotes, the backslash
     characters must be doubled, because they are significant in quoted
     strings. The following two settings are exactly equivalent:

          host_reject = ^(a|b)\.c\.d$
          host_reject = "^(a|b)\\.c\\.d$"

   * If the item is of the form

          <search-type>;<filename or query>

     for example

          dbm;/host/accept/list

     then the host name is looked up using the search type and file
     name or query (as appropriate). If the lookup succeeds, the host
     matches the item. The actual data that is looked up is not used.

     Warning: when using this kind of lookup, you must have host names
     as keys in the file, not IP addresses. If you want to do lookups
     based on IP addresses, you must precede the search type with
     `net-' (see above). There is, however, no reason why you could not
     use two items in a list, one doing an address lookup and one doing
     a name lookup, both using the same file.


File: exim.info,  Node: Mixing host names and addresses in host lists,  Next: Use of RFC 1413 identification in host lists,  Prev: Host lists,  Up: The Exim configuration file

Mixing host names and addresses in host lists
=============================================

If you have both names and IP addresses in the same host list, you
should normally put the IP addresses first. For example:

     host_accept_relay = 10.9.8.7 : *.friends.domain

The reason for this lies in the left-to-right way that Exim processes
lists.  It can test IP addresses without doing any DNS lookups, but
when it reaches an item that requires a DNS lookup, it normally fails
if the DNS lookup fails, because it cannot find a host name to compare
with the pattern. (There is the `+allow_unknown' facility - described
above - for changing this, but it is not recommended.) If the above
list were in the other order, Exim would reject relaying from any host
whose name could not be found, even if it were 10.9.8.7.


File: exim.info,  Node: Use of RFC 1413 identification in host lists,  Next: Address lists,  Prev: Mixing host names and addresses in host lists,  Up: The Exim configuration file

Use of RFC 1413 identification in host lists
============================================

Any item in a host list (other than a plain file name or
`+allow_unknown') can optionally be preceded by

     <ident>@
     or
     !<ident>@

where <ident> is an RFC 1413 identification string. For example,

     host_reject = !exim@my.mail.gate:192.168.111.111:!root@public.host

If an <ident> string is present, it must match the RFC 1413
identification sent by the remote host, unless it is preceded by an
exclamation mark, in which case it must not match. The remainder of the
item, following the @, may be either positive or negative.


File: exim.info,  Node: Address lists,  Next: Case of letters in address lists,  Prev: Use of RFC 1413 identification in host lists,  Up: The Exim configuration file

Address lists
=============

Address lists are constructed as described in section "List
construction". They contain patterns which are matched against mail
addresses.  As in the case of domain lists, the list is searched from
left to right, any item may be preceded by an exclamation mark to
negate it, and a plain file name may appear as an entire item, causing
each line of the file to be read and treated as a separate pattern.
Because local parts may legitimately contain # characters, a comment in
the file is recognized only if # is followed by white space or the end
of the line.

The following kinds of pattern may appear inline or as lines in an
included file:

   * If a pattern starts with ^ then a regular expression match is done
     against the complete address, using the entire pattern as the
     regular expression.

   * Otherwise, if there is no @ in the pattern, it is first matched
     against the domain part of the subject address, the local part
     being ignored. This match is done exactly as for an entry in a
     domain list, so, for example, the item may begin with * or it may
     be a (partial) lookup (see section "Domain lists").  If there is
     no match, and the pattern consists of a single lookup, the entire
     subject address is looked up in the file, with partial matching
     disabled. This means that an item such as

          sender_reject_recipients = partial-dbm;/black/list

     can reference a single file whose keys are a mixture of complete
     domains, partial domains, and individual mail addresses.

     Note that this is not an `include' facility when the lookup type
     is "lsearch".  The keys in the file are not interpreted specially,
     as they would be if they appeared as individual items in the
     address list, or lines in a file given as a plain file name
     without a search type.

     You might think of using a lookup type ending in *@ (as described
     in section "Default values in single-key lookups" in chapter "File
     and database lookups") to match entries in a file of the form

          *@penguin.book

     However, this does not currently work, because the presence of an
     @ in the pattern causes Exim to think the item is one of the forms
     described below. In some future release this may be changed.
     Meanwhile, the effect you want (matching any local part at a
     particular domain) is achieved by simply listing the domain name
     in the file.

   * If the pattern starts with `@@<lookup-item>' (for example,
     `@@lsearch;/some/file'), the address that is being checked is
     split into a local part and a domain. The domain is looked up in
     the file. If it is not found, there is no match. If it is found,
     the data that is looked up from the file is treated as a
     colon-separated list of local part patterns, each of which is
     matched against the subject local part in turn.

     The lookup may be a partial one, and/or one involving a search for
     a default keyed by `*'. The local part patterns that are looked up
     can be regular expressions or begin with `*', or even be further
     lookups.  They may also be independently negated. For example, with

          sender_reject_recipients = @@dbm;/etc/reject-by-domain

     the data from which DBM file is built could contain lines like

          baddomain.com:  !postmaster : *

     If a local part that actually begins with an exclamation mark is
     required, it has to be specified using a regular expression.  In
     "lsearch" files, an entry may be split over several lines by
     indenting the second and subsequent lines, but the separating
     colon must still be included at line breaks. White space
     surrounding the colons is ignored. For example:

          aol.com:  spammer1 : spammer2 : ^[0-9]+$ :
                    spammer3 : spammer4

     As in all colon-separated lists in Exim, a colon can be included
     in an item by doubling.

     If the last item in the list starts with a right angle-bracket, the
     remainder of the item is taken as a new key to look up in order to
     obtain a continuation list of local parts. The new key can be any
     sequence of characters. Thus one might have entries like

          aol.com: spammer1 : spammer 2 : >*
          xyz.com: spammer3 : >*
          *:       ^\d{8}$

     in a file that was searched with "@@dbm*", to specify a match for
     8-digit local parts for all domains, in addition to the specific
     local parts listed for each domain. Of course, using this feature
     costs another lookup each time a chain is followed, but the effort
     needed to maintain the data is reduced.  It is possible to
     construct loops using this facility, and in order to catch them,
     the chains may be no more than fifty items long.

   * If none of the above cases apply, the local part of the subject
     address is compared with the local part of the pattern, which may
     start with an asterisk.  If the local parts match, the domains are
     compared in exactly the same way as entries in a domain list,
     except that a regular expression is not permitted for a domain
     only. However, file lookups are permitted. For example:

          sender_reject = *@*.spamming.site:\
                          bozo@partial-lsearch;/list/of/dodgy/sites

     The domain may be given as a single @ character, as in a domain
     list, standing for the local host name, leading to items of the
     form `user@@'.  If a local part that actually begins with an
     exclamation mark is required, it has to be specified using a
     regular expression, as otherwise the exclamation mark is treated
     as a sign of negation.


File: exim.info,  Node: Case of letters in address lists,  Prev: Address lists,  Up: The Exim configuration file

Case of letters in address lists
================================

Domains in email addresses are always handled caselessly, but for local
parts case may be significant on some systems (see "locally_caseless"
for how Exim deals with this when processing local addresses). However,
RFC 2505 (Anti-Spam Recommendations for SMTP MTAs) suggests that
matching of addresses to blocking lists should be done in a
case-independent manner. Since most address lists in Exim are used for
this kind of control, Exim attempts to do this by default.

The domain portion of an address is always lowercased before matching
it to an address list. The local part is lowercased by default, and any
string comparisons that take place are done caselessly. This means that
the data in the address list itself, in files included as plain file
names, and in any file that is looked up using the `@@' mechanism, can
be in any case. However, the keys in files that are looked up by a
search type other than "lsearch" (which works caselessly) must be in
lower case, because these lookups are not case-independent.

To allow for the possibility of caseful address list matching, if an
item in the list is the string `+caseful' then the original case of the
local part is restored for any comparisons that follow, and string
comparisons are no longer case-independent.  This does not affect the
domain, which remains in lower case. However, although independent
matches on the domain alone are still performed caselessly, regular
expressions that match against an entire address are by default caseful
after `+caseful' has been seen.


File: exim.info,  Node: Regular expressions,  Next: String expansions,  Prev: The Exim configuration file,  Up: Top

Regular expressions
*******************

Exim uses the PCRE regular expression library; this provides regular
expression matching that is compatible with Perl 5. The syntax and
semantics of these regular expressions is discussed in many Perl
reference books, and also in Jeffrey Friedl's Mastering Regular
Expressions  (O'Reilly, ISBN 1-56592-257-3).

The documentation for PCRE, in plain text and HTML, is included in the
"doc" directory of the Exim distribution. This describes the features
of the regular expressions that PCRE supports, so no further
description is included here. The PCRE functions are called from Exim
using the default option settings, except that the PCRE_CASELESS option
is set when the matching is required to be independent of the case of
letters.



* Menu:

* Testing regular expressions::


File: exim.info,  Node: Testing regular expressions,  Prev: Regular expressions,  Up: Regular expressions

Testing regular expressions
===========================

A program called "pcretest" forms part of the PCRE distribution and is
built with PCRE during the process of building Exim. It is primarily
intended for testing PCRE itself, but it can also be used for
experimenting with regular expressions. The binary can be found in the
"util" sub-directory of the Exim build directory. There is
documentation of various options in "doc/pcretest.txt", but for simple
testing, none are needed. This is the output of a sample run of
"pcretest":

       re> /^([^@]+)@.+\.(ac|edu)\.(?!kr)[a-z]{2}$/
     data> x@y.ac.uk
      0: x@y.ac.uk
      1: x
      2: ac
     data> x@y.ac.kr
     No match
     data> x@y.edu.com
     No match
     data> x@y.edu.co
      0: x@y.edu.co
      1: x
      2: edu

After the `re>' prompt, a regular expression enclosed in delimiters is
expected. If this compiles without error, `data>' prompts are given for
strings against which the expression is matched. An empty data line
causes a new regular expression to be read. If the match is successful,
the captured substring values (that is, what would be in the variables
$0, $1, $2, etc.) are shown. The above example tests for an email
address whose domain ends with either `ac' or `edu' followed by a
two-character top-level domain that is not `kr'. The local part is
captured in $1 and the `ac' or `edu' in $2.


File: exim.info,  Node: String expansions,  Next: Embedded Perl,  Prev: Regular expressions,  Up: Top

String expansions
*****************

A number of configuration strings are expanded before use. Some of them
are expanded every time they are used; others are expanded only once.

Expanded strings are copied verbatim from left to right except when a
dollar or backslash character is encountered. A dollar specifies the
start of a portion of the string which is interpreted and replaced as
described below.

An uninterpreted dollar can be included in the string by putting a
backslash in front of it - if the string appears in quotes in the
configuration file, two backslashes are required because the quotes
themselves cause interpretation of backslashes when the string is read
in. A backslash can be used to prevent any special character being
treated specially in an expansion, including itself.

A backslash followed by one of the letters `n', `r', or `t' is
recognized as an escape sequence for the character newline, carriage
return, or tab, respectively. A backslash followed by up to three octal
digits is recognized as an octal encoding for a single character, while
a backslash followed by `x' and up to two hexadecimal digits is a
hexadecimal encoding. A backslash followed by any other character
causes that character to be added to the output string uninterpreted.
These escape sequences are also recognized in quoted strings as they
are read in; their interpretation in expansions as well is useful for
unquoted strings and other cases such as looked-up strings that are then
expanded.



* Menu:

* Testing string expansions::
* Expansion items::
* Expansion operators::
* Expansion conditions::
* Expansion variables::


File: exim.info,  Node: Testing string expansions,  Next: Expansion items,  Prev: String expansions,  Up: String expansions

Testing string expansions
=========================

Many expansions can be tested by calling Exim with the -be option. This
takes the command arguments, or lines from the standard input if there
are no arguments, runs them through the string expansion code, and
writes the results to the standard output. Variables based on
configuration values are set up, but since no message is being
processed, variables such as $local_part have no value. Nevertheless
the -be option can be useful for checking out file and database
lookups, and the use of expansion operators such as "substr" and "hash".

Exim gives up its root privilege when it is called with the -be option,
and instead runs under the uid and gid it was called with, to prevent
users from using -be for reading files to which they normally do not
have access.


File: exim.info,  Node: Expansion items,  Next: Expansion operators,  Prev: Testing string expansions,  Up: String expansions

Expansion items
===============

The following items are recognized in expanded strings. White space may
be used between sub-items that are keywords or substrings enclosed in
braces inside an outer set of braces, to improve readability.  Within
braces, however, white space is significant.

     [(font color=blue)]______________________________________________________________[(/font)]
     
     $<variable name> or ${<variable name>}

Substitute the contents of the named variable, for example

     $local_part
     ${domain}

The second form can be used to separate the name from subsequent
alphanumeric characters. This form (using curly brackets) is available
only for variables; it does not apply to message headers. The names of
the variables are given in section "Expansion variables" below. If the
name of a non-existent variable is given, the expansion fails.

     [(font color=blue)]______________________________________________________________[(/font)]
     
     $header_<header name>: or $h_<header name>:

Substitute the contents of the named message header line, for example

     $header_reply-to:

The header names follow the syntax of RFC 822, which states that they
may contain any printing characters except space and colon.
Consequently, curly brackets do not terminate header names, and should
not be used to enclose them as if they were variables. Attempting to do
so causes a syntax error.

Upper-case and lower-case letters are synonymous in header names. If the
following character is white space, the terminating colon may be
omitted, but this is not recommended, because you may then forget it
when it is needed. When white space terminates the header name, it is
included in the expanded string.  If the message does not contain the
given header, the expansion item is replaced by an empty string. (See
the "def" condition in section "Expansion conditions" for a means of
testing for the existence of a header.)  If there is more than one
header with the same name, they are all concatenated to form the
substitution string, with a newline character between each of them.
However, if the length of this string exceeds 64K, any further headers
of the same name are ignored.

     [(font color=blue)]______________________________________________________________[(/font)]
     
     ${<op>:<string>}

The string is first itself expanded, and then the operation specified
by <op> is applied to it. For example,

     ${lc:$local_part}

A list of operators is given in section "Expansion operators" below. The
string starts with the first character after the colon, which may be
leading white space.

     [(font color=blue)]______________________________________________________________[(/font)]
     
     ${extract{<key>}{<string1>}{<string2>}{<string3>}}

The key and <string1> are first expanded separately. The key must not
consist entirely of digits. For the string, the result must be of the
form:

     <key1> = <value1>  <key2> = <value2> ...

where the equals signs and spaces are optional. If any of the values
contain white space, they must be enclosed in double quotes, and any
values that are enclosed in double quotes are subject to escape
processing as described in section "String" in chapter "The Exim
configuration file". The expanded <string1> is searched for the value
that corresponds to the key. If it is found, <string2> is expanded, and
replaces the whole item; otherwise <string3> is used. During the
expansion of <string2> the variable $value contains the value that has
been extracted.  Afterwards, it is restored to any previous value it
might have had.

If {<string3>} is omitted, the item is replaced by an empty string if
the key is not found. If {<string2>} is also omitted, the value that
was looked up is used. Thus, for example, these two expansions are
identical, and yield `2001':

     ${extract{gid}{uid=1984 gid=2001}}
     ${extract{gid}{uid=1984 gid=2001}{$value}}

Instead of {<string3>} the word `fail' (not in curly brackets) can
appear, for example:

     ${extract{Z}{A=... B=...}{$value} fail }

{<string2>} must be present for `fail' to be recognized. When this
syntax is used, if the extraction fails, the entire string expansion
fails in a way that can be detected by the code in Exim which requested
the expansion. This is called `forced expansion failure', and its
consequences depend on the circumstances. In some cases it is no
different from any other expansion failure, but in others a different
action may be taken. See for example the "new_address" option of the
"smartuser" director.

     [(font color=blue)]______________________________________________________________[(/font)]
     
     ${extract{<number>}{<separators>}{<string1>}{<string2>}{<string3>}}

The <number> argument must consist entirely of decimal digits. This is
what distinguishes this form of "extract" from the previous kind. It
behaves in the same way, except that, instead of extracting a named
field, it extracts from <string1> the field whose number is given as
the first argument. The first field is numbered one. If the number is
greater than the number of fields in the string, the result is the
expansion of <string3>, or the empty string if <string3> is not
provided.  If the number is zero, the entire string is returned. The
fields in the string are separated by any one of the characters in the
separator string. For example:

     ${extract{2}{:}{x:42:99:& Mailer::/bin/bash}}

yields `42'. Two successive separators mean that the field between them
is empty (for example, the fifth field above).

     [(font color=blue)]______________________________________________________________[(/font)]
     
     ${if <condition> {<string1>}{<string2>}}

If <condition> is true, <string1> is expanded and replaces the whole
item; otherwise <string2> is used. For example,

     ${if eq {$local_part}{postmaster} {yes}{no} }

The second string need not be present; if it is not and the condition
is not true, the item is replaced with nothing. Alternatively, the word
`fail' may be present instead of the second string (without any curly
brackets). In this case, the expansion is forced to fail if the
condition is not true. The available conditions are described in
section "Expansion conditions" below.

     [(font color=blue)]______________________________________________________________[(/font)]
     
     ${lookup{<key>} <search type> {<file>} {<string1>} {<string2>}}

     ${lookup <search type> {<query>} {<string1>} {<string2>}}

These items specify data lookups in files and databases, as discussed in
chapter "File and database lookups". The first form is used for
single-key lookups, and the second is used for query-style lookups. The
<key>, <file>, and <query> strings are expanded before use.

If there is any white space in a lookup item which is part of a filter
command, a rewrite rule, a routing rule for the "domainlist" router, or
any other place where white space is significant, the lookup item must
be enclosed in double quotes.  The use of data lookups in users' filter
files may be locked out by the system administrator.

If the lookup succeeds, <string1> is expanded and replaces the entire
item.  During its expansion, the variable $value contains the data
returned by the lookup.  Afterwards it reverts to the value it had
previously (at the outer level it is empty).  If the lookup fails,
<string2> is expanded and replaces the entire item. If {<string2>} is
omitted, the replacement is null on failure. Alternatively, <string2>
can itself be a nested lookup, thus providing a mechanism for looking
up a default value when the original lookup fails.

If a nested lookup is used as part of <string1>, $value contains the
data for the outer lookup while the parameters of the second lookup are
expanded, and also while <string2> of the second lookup is expanded,
should the second lookup fail.

Instead of {<string2>} the word `fail' can appear, and in this case, if
the lookup fails, the entire expansion is forced to fail. If both
{<string1>} and {<string2>} are omitted, the result is the looked up
value in the case of a successful lookup, and nothing in the case of
failure.

For single-key lookups, the string `partial-' is permitted to precede
the search type in order to do partial matching, and * or *@ may follow
a search type to request default lookups if the key does not match (see
sections "Default values in single-key lookups" in chapter "File and
database lookups" and "Partial matching in single-key lookups" in
chapter "File and database lookups").

If a partial search is used, the variables $1 and $2 contain the wild
and non-wild parts of the key during the expansion of the replacement
text.  They return to their previous values at the end of the lookup
item.

This example looks up the postmaster alias in the conventional alias
file.

     ${lookup {postmaster} lsearch {/etc/aliases} {$value}}

This example uses NIS+ to look up the full name of the user
corresponding to the local part of an address, forcing the expansion to
fail if it is not found.

     "${lookup nisplus {[name=$local_part],passwd.org_dir:gcos} \
       {$value}fail}"

     [(font color=blue)]______________________________________________________________[(/font)]
     
     ${lookup{<key:subkey>} <search type> {<file>} {<string1>} {<string2>}}

This is just a syntactic variation for a single-key lookup, surrounded
by an "extract" item. It searches for <key> in the file as described
above for single-key lookups; if it succeeds, it extracts from the data
a subfield which is identified by the <subkey>. For example, if a line
in a linearly searched file contains

     alice: uid=1984 gid=2001

then expanding the string

     ${lookup{alice:uid}lsearch{<file name>}{$value}}

yields the string `1984'. If the subkey is not found in the looked up
data, then <string2>, if present, is expanded and replaces the entire
item.  Otherwise the replacement is null. The example above could
equally well be written like this:

     ${extract{uid}{${lookup{alice}lsearch{<file name>}}}}

and this is recommended, because this approach can also be used with
query-style lookups.

     [(font color=blue)]______________________________________________________________[(/font)]
     
     ${perl{<subroutine>}{<arg>}{<arg>}...}

This item is available only if Exim has been built to include an
embedded Perl interpreter. The subroutine name and the arguments are
first separately expanded, and then the Perl subroutine is called with
those arguments. No arguments need be given; the maximum number
permitted is eight.

The return value of the subroutine is inserted into the expanded
string, unless the return value is "undef". In that case, the expansion
fails in the same way as an explicit `fail' on a lookup item. If the
subroutine exits by calling Perl's "die" function, the expansion fails
with the error message that was passed to "die".

More details of the embedded Perl facility are given in chapter
"Embedded Perl".

     [(font color=blue)]______________________________________________________________[(/font)]
     
     ${sg{<subject>}{<regex>}{<replacement>}}

This item works like Perl's substitution operator (s) with the global
(/g) option; hence its name. It takes three arguments: the subject
string, a regular expression, and a substitution string. For example

     ${sg{abcdefabcdef}{abc}{xyz}}

yields `xyzdefxyzdef'. Because all three arguments are expanded before
use, if any $ or \ characters are required in the regular expression or
in the substitution string, they have to be escaped. For example

     ${sg{abcdef}{^(...)(...)\$}{\$2\$1}}

yields `defabc', and

     ${sg{1=A 4=D 3=C}{(\\d+)=}{K\$1=}}

yields `K1=A K4=D K3=C'.

     [(font color=blue)]______________________________________________________________[(/font)]
     
     ${tr{<subject>}{<characters>}{<replacements>}}

This item does single-character translation on its subject string. The
second argument is a list of characters to be translated in the subject
string. Each matching character is replaced by the corresponding
character from the replacement list. For example

     ${tr{abcdea}{ac}{13}}

yields `1b3de1'. If there are duplicates in the second character
string, the last occurrence is used. If the third string is shorter
than the second, its last character is replicated. However, if it is
empty, no translation takes place.


File: exim.info,  Node: Expansion operators,  Next: Expansion conditions,  Prev: Expansion items,  Up: String expansions

Expansion operators
===================

The following operations can be performed on portions of an expanded
string.  The substring is first expanded before the operation is
applied to it.

     [(font color=blue)]______________________________________________________________[(/font)]
     
     ${domain:<string>}

The string is interpreted as an RFC 822 address and the domain is
extracted from it. If the string does not parse successfully, the
result is empty.

     [(font color=blue)]______________________________________________________________[(/font)]
     
     ${escape:<string>}

If the string contains any non-printing characters, they are converted
to escape sequences starting with a backslash.  Whether characters with
the most significant bit set (so-called `8-bit characters') count as
printing or not is controlled by the "print_topbitchars" option.

     [(font color=blue)]______________________________________________________________[(/font)]
     
     ${expand:<string>}

The "expand" operator causes a string to be expanded for a second time.
For example,

     ${expand:${lookup{$domain}dbm{/some/file}{$value}}}

first looks up a string in a file while expanding the operand for
"expand", and then re-expands what it has found.

     [(font color=blue)]______________________________________________________________[(/font)]
     
     ${hash_<n>_<m>:<string>}

The two items <n> and <m> are numbers. If <n> is greater than or equal
to the length of the string, the operator returns the string. Otherwise
it computes a new string of length <n> by applying a hashing function
to the string. The new string consists of characters taken from the
first <m> characters of the string

     abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQWRSTUVWXYZ0123456789

and if <m> is not present the value 26 is used, so that only lower case
letters appear. These examples:

     ${hash_3:monty}
     ${hash_5:monty}
     ${hash_4_62:monty python}

yield

     jmg
     monty
     fbWx

respectively. The abbreviation "h" can be used instead of "hash".

     [(font color=blue)]______________________________________________________________[(/font)]
     
     ${nhash_<n>:<string>}

The string is processed by a hash function which returns a numeric
value in the range 0-<n>-1.

     [(font color=blue)]______________________________________________________________[(/font)]
     
     ${nhash_<n>_<m>:<string>}

The string is processed by a div/mod hash function which returns two
numbers, separated by a slash, in the ranges 0-<n>-1 and 0-<m>-1,
respectively. For example,

     ${nhash_8_64:supercalifragilisticexpialidocious}

returns the string `6/33'.

     [(font color=blue)]______________________________________________________________[(/font)]
     
     ${md5:<string>}

The "md5" operator computes the MD5 hash value of the string, and
returns it as a 32-digit hexadecimal number.

     [(font color=blue)]______________________________________________________________[(/font)]
     
     ${lc:<string>}

This forces the letters in the string into lower-case, for example:

     ${lc:$local_part}

     [(font color=blue)]______________________________________________________________[(/font)]
     
     ${uc:<string>}

This forces the letters in the string into upper-case.

     ${length_<number>:<string>}

The "length" operator can be used to extract the initial portion of a
string.  It is followed by an underscore and the number of characters
required. For example

     ${length_50:$message_body}

The result of this operator is either the first <number> characters or
the whole string, whichever is the shorter. The abbreviation "l" can be
used instead of "length".

     [(font color=blue)]______________________________________________________________[(/font)]
     
     ${local_part:<string>}

The string is interpreted as an RFC 822 address and the local part is
extracted from it. If the string does not parse successfully, the
result is empty.

     ${mask:<IP address>/<bit count>}

If the form of the string to be operated on is not an IP address
followed by a slash and an integer, the expansion fails. Otherwise,
this operator converts the IP address to binary, masks off the least
significant bits according to the bit count, and converts the result
back to text, with mask appended. For example,

     ${mask:10.111.131.206/28}

returns the string `10.111.131.192/28'. Since this operation is
expected to be mostly used for looking up masked addresses in files,
the result for an IPv6 address uses fullstops (periods) to separate
components instead of colons, because colon terminates a key string in
lsearch files. So, for example,

     ${mask:5f03:1200:836f:0a00:000a:0800:200a:c031/99}

returns the string

     5f03.1200.836f.0a00.000a.0800.2000.0000/99

Letters in IPv6 addresses are always output in lower case.

     [(font color=blue)]______________________________________________________________[(/font)]
     
     ${quote:<string>}

The "quote" operator puts its argument into double quotes if it contains
anything other than letters, digits, underscores, full stops (periods),
and hyphens. Any occurrences of double quotes and backslashes are
escaped with a backslash. For example,

     ${quote:ab"*"cd}

becomes

     "ab\"*\"cd"

The place where this is useful is when the argument is a substitution
from a variable or a message header.

     [(font color=blue)]______________________________________________________________[(/font)]
     
     ${quote_<lookup-type>:<string>}

This operator applies lookup-specific quoting rules to the string. Each
query-style lookup type has its own quoting rules which are described
with the lookups in chapter "File and database lookups". For example,

     ${quote_ldap:two + two}

returns `two%20%5C+%20two'. For single-key lookup types, no quoting is
necessary and this operator yields an unchanged string.

     [(font color=blue)]______________________________________________________________[(/font)]
     
     ${rxquote:<string>}

The "rxquote" operator inserts a backslash before any non-alphanumeric
characters in its argument. This is useful when substituting the values
of variables or headers inside regular expressions.

     [(font color=blue)]______________________________________________________________[(/font)]
     
     ${substr_<start>_<length>:<string>}

The "substr" operator can be used to extract more general substrings
than "length". It is followed by an underscore and the starting offset,
then a second underscore and the length required. For example

     ${substr_3_2:$local_part}

If the starting offset is greater than the string length the result is
the null string; if the length plus starting offset is greater than the
string length, the result is the right-hand part of the string,
starting from the given offset. The first character in the string has
offset zero. The abbreviation "s" can be used instead of "substr".

The "substr" expansion operator can take negative offset values to count
from the righthand end of its operand. The last character is offset -1,
the second-last is offset -2, and so on. Thus, for example,

     ${substr_-5_2:1234567}

yields `34'. If the absolute value of a negative offset is greater than
the length of the string, the substring starts at the beginning of the
string, and the length is reduced by the amount of overshoot. Thus, for
example,

     ${substr_-5_2:12}

yields an empty string, but

     ${substr_-3_2:12}

yields `1'.

If the second number is omitted from "substr", the remainder of the
string is taken if the offset was positive. If it was negative, all
characters in the string preceding the offset point are taken. For
example, an offset of -1 and no length yields all but the last
character of the string.


File: exim.info,  Node: Expansion conditions,  Next: Expansion variables,  Prev: Expansion operators,  Up: String expansions

Expansion conditions
====================

The following conditions are available for testing by the "${if"
construct while expanding strings:

     [(font color=blue)]______________________________________________________________[(/font)]
     
     !<condition>

Preceding any condition with an exclamation mark negates the result of
the condition.

     <symbolic operator> {<string1>}{<string2>}

There are a number of symbolic operators for doing numeric comparisons.
They are:

     =        equal
     ==       equal
     >        greater
     >=       greater or equal
     <        less
     <=       less or equal

For example,

     ${if >{$message_size}{10M} ...

Note that the general negation operator provides for inequality testing.
The two strings must take the form of optionally signed decimal
integers, optionally followed by one of the letters `K' or `M' (in
either upper or lower case), signifying multiplication by 1024 or
1024*1024, respectively.

     [(font color=blue)]______________________________________________________________[(/font)]
     
     def:<variable name>

The "def" condition must be followed by the name of one of the expansion
variables defined in section "Expansion variables".  The condition is
true if the named expansion variable does not contain the empty string,
for example

     ${if def:sender_ident {from $sender_ident}}

Note that the variable name is given without a leading "$" character.
If the variable does not exist, the expansion fails.

     [(font color=blue)]______________________________________________________________[(/font)]
     
     def:header_<header name>:  or  def:h_<header name>:

This condition is true if a message is being processed and the named
header exists in the message. For example,

     ${if def:header_reply-to:{$h_reply-to:}{$h_from:}}

Note that no "$" appears before "header_" or "h_" in the condition, and
that header names must be terminated by colons if white space does not
follow.

     [(font color=blue)]______________________________________________________________[(/font)]
     
     exists {<file name>}

The substring is first expanded and then interpreted as an absolute
path.  The condition is true if the named file (or directory) exists.
The existence test is done by calling the "stat()" function.  The use
of the "exists" test in users' filter files may be locked out by the
system administrator.

     eq {<string1>}{<string2>}

The two substrings are first expanded. The condition is true if the two
resulting strings are identical, including the case of letters.

     [(font color=blue)]______________________________________________________________[(/font)]
     
     crytpeq {<string1>}{<string2>}

This condition is included in the Exim binary if it is built to support
any authentication mechanisms (see chapter "SMTP authentication").
Otherwise, it is necessary to define SUPPORT_CRYPTEQ in
`Local/Makefile' to get "crypteq" included in the binary.

The "crypteq" condition has two arguments. The first is encrypted and
compared against the second, which is already encrypted. The second
string may be in the LDAP form for storing encrypted strings, which
starts with the encryption type in curly brackets, followed by the
data. For example:

     {md5}CY9rzUYh03PK3k6DJie09g==

If such a string appears directly in an expansion, the curly brackets
have to be quoted, because they are part of the expansion syntax. For
example:

     ${if crypteq {test}{\{md5\}CY9rzUYh03PK3k6DJie09g==}{yes}{no}}

Two encryption types are currently supported:

   * "md5" first computes the MD5 digest of the string, and then
     expresses this as printable characters by means of base64 encoding.

   * "crypt" calls the "crypt()" function as used for encrypting login
     passwords.

If the second string does not begin with `{' it is assumed to be
encrypted with "crypt()", since such strings cannot begin with `{'.
Typically this will be a field from a password file.

     [(font color=blue)]______________________________________________________________[(/font)]
     
     match {<string1>}{<string2>}

The two substrings are first expanded. The second is then treated as a
regular expression and applied to the first. Because of the
pre-expansion, if the regular expression contains dollar, or backslash
characters, they must be escaped with backslashes. Care must also be
taken if the regular expression contains braces (curly brackets). A
closing brace must be escaped so that it is not taken as a premature
termination of <string2>. It does no harm to escape opening braces, but
this is not strictly necessary. For example,

     ${if match {$local_part}{^\\d\{3\}} ...

If the whole expansion string is in double quotes, further escaping of
backslashes is also required.

The condition is true if the regular expression match succeeds. At the
start of an "if" expansion the values of the numeric variable
substitutions $1 etc.  are remembered. Obeying a "match" condition that
succeeds causes them to be reset to the substrings of that condition
and they will have these values during the expansion of the success
string. At the end of the "if" expansion, the previous values are
restored. After testing a combination of conditions using "or", the
subsequent values of the numeric variables are those of the condition
that succeeded.

     [(font color=blue)]______________________________________________________________[(/font)]
     
     pam {<string1>:<string2>:...}

"Pluggable Authentication Modules"
(http://www.kernel.org/pub/linux/libs/pam/) are a facility which is
available in the latest releases of Solaris and in some GNU/Linux
distributions. The Exim support, which is intended for use in
conjunction with the SMTP AUTH command, is available only if Exim is
compiled with

     SUPPORT_PAM=yes

in `Local/Makefile'. You probably need to add -lpam to EXTRALIBS, and
in some releases of GNU/Linux -ldl is also needed.

The argument string is first expanded, and the result must be a
colon-separated list of strings. The PAM module is initialized with the
service name `exim' and the user name taken from the first item in the
colon-separated data string (i.e. <string1>). The remaining items in
the data string are passed over in response to requests from the
authentication function. In the simple case there will only be one
request, for a password, so the data will consist of just two strings.

There can be problems if any of the strings are permitted to contain
colon characters. In the usual way, these have to be doubled to avoid
being taken as separators. If the data is being inserted from a
variable, the "sg" expansion item can be used to double any existing
colons. For example, the configuration of a LOGIN authenticator might
contain this setting:

     server_condition = ${if pam{$1:${sg{$2}{:}{::}}}{yes}{no}}

     [(font color=blue)]______________________________________________________________[(/font)]
     
     first_delivery

This condition, which has no data, is true during a message's first
delivery attempt. It is false during any subsequent delivery attempts.

     [(font color=blue)]______________________________________________________________[(/font)]
     
     queue_running

This condition, which has no data, is true during delivery attempts
that are initiated by queue-runner processes, and false otherwise.

     [(font color=blue)]______________________________________________________________[(/font)]
     
     or {{<cond1>}{<cond2>}...}

The sub-conditions are evaluated from left to right. The condition is
true if any one of the sub-conditions is true.  For example,

     ${if or {{eq{$local_part}{spqr}}{eq{$domain}{testing.com}}}...

When a true sub-condition is found, the following ones are parsed but
not evaluated. If there are several `match' sub-conditions the values
of the numeric variables afterwards are taken from the first one that
succeeds.

     [(font color=blue)]______________________________________________________________[(/font)]
     
     and {{<cond1>}{<cond2>}...}

The sub-conditions are evaluated from left to right. The condition is
true if all of the sub-conditions are true.  If there are several
`match' sub-conditions, the values of the numeric variables afterwards
are taken from the last one.  When a false sub-condition is found, the
following ones are parsed but not evaluated.

Note that "and" and "or" are complete conditions on their own, and
precede their lists of sub-conditions. Each sub-condition must be
enclosed in braces within the overall braces that contain the list. No
repetition of "if" is used.


File: exim.info,  Node: Expansion variables,  Prev: Expansion conditions,  Up: String expansions

Expansion variables
===================

The variable substitutions that are available for use in expansion
strings are:

$0, $1, etc: When a "matches" expansion condition succeeds, these
variables contain the captured substrings identified by the regular
expression during subsequent processing of the success string of the
containing "if" expansion item. They may also be set externally by some
other matching process which precedes the expansion of the string. For
example, the commands available in Exim filter files include an "if"
command with its own regular expression matching condition.

$address_file: When, as a result of aliasing or forwarding, a message is
directed to a specific file, this variable holds the name of the file
when the transport is running. For example, using the default
configuration, if user "r2d2" has a `.forward' file containing

     /home/r2d2/savemail

then when the "address_file" transport is running, $address_file
contains `/home/r2d2/savemail'. At other times, the variable is empty.

$address_pipe: When, as a result of aliasing or forwarding, a message is
directed to a pipe, this variable holds the pipe command when the
transport is running.

$authenticated_id: When a server successfully authenticates a client it
may be configured to preserve some of the authentication information in
the variable $authenticated_id (see chapter "SMTP authentication"). For
example, a user/password authenticator configuration might preserve the
user name for use in the directors or routers.

$authenticated_sender: When a client host has authenticated itself,
Exim pays attention to the AUTH= parameter on the SMTP MAIL command,
provided the setting of "server_mail_auth_condition" (see chapter "SMTP
authentication") permits it.  Otherwise, it accepts the syntax, but
ignores the data. Unless the data is the string `<>', it is set as the
authenticated sender of the message, and the value is available during
delivery in the $authenticated_sender variable.

$body_linecount: When a message is being received or delivered, this
variable contains the number of lines in the message's body.

 aller_gid: The group id under which the process that called Exim was
running.
This is not the same as the group id of the originator of a message
(see $originator_gid). If Exim re-execs itself, this variable in the new
incarnation normally contains the Exim gid.

  aller_uid: The user id under which the process that called Exim was
running.
This is not the same as the user id of the originator of a message (see
$originator_uid). If Exim re-execs itself, this variable in the new
incarnation normally contains the Exim uid.

     ompile_date: The date on which the Exim binary was compiled.
 ompile_number: The building process for Exim keeps a count of the number
of
times it has been compiled. This serves to distinguish different
compilations of the same version of the program.

$domain: When an address is being directed, routed, or delivered on its
own, this variable contains the domain. In particular, it is set during
user filtering, but not during system filtering, since a message may
have many recipients and the system filter is called just once.

For remote addresses, the domain that is being routed can change as
routing proceeds, as a result of router actions (see, for example, the
"domainlist" router). However, the value of $domain remains as the
original domain. The current routing domain can often be accessed by
other means.

When a remote or local delivery is taking place, if all the addresses
that are being handled simultaneously contain the same domain, it is
placed in $domain. Otherwise this variable is empty. Transports should
be restricted to handling only one domain at once if its value is
required at transport time - this is the default for local transports.
For further details of the environment in which local transports are
run, see chapter "Environment for running local transports".

At the end of a delivery, if all deferred addresses have the same
domain, it is set in $domain during the expansion of
"delay_warning_condition".

Because configured address rewriting happens at the time a message is
received, $domain normally contains the value after rewriting. However,
when a rewrite item is actually being processed (see chapter "Address
rewriting") $domain contains the domain portion of the address that is
being rewritten; it can be used in the expansion of the replacement
address, for example, to rewrite domains by file lookup.

When the "smtp_etrn_command" option is being expanded, $domain contains
the complete argument of the ETRN command (see section "The ETRN
command" in chapter "SMTP processing").

$domain_data: When a director or a router has a setting of the "domains"
generic option, and that involves a lookup which succeeds, the data
read by the lookup is available during the running of the director or
router as $domain_data. In addition, if the driver directs or routes
the address to a transport, the value is available in that transport.
In all other situations, this variable expands to nothing.

							rrmsg_recipient: This is set to the recipient address of an error
message while Exim is creating it. It is useful if a customized error
message text file is in use (see chapter "Customizing error and warning
messages").

$home: A home directory may be set during a local delivery, either by
the transport or by the director that handled the address. When this is
the case, $home contains its value and may be used in any expanded
options for the transport.  The "forwardfile" director also makes use
of $home. Full details are given in chapter "The forwardfile director".
When interpreting a user's filter file, Exim is normally configured so
that $home contains the user's home directory.  When running a filter
test via the -bf option, $home is set to the value of the environment
variable HOME.

$host: When the "smtp" transport is expanding its options for
encryption using TLS, $host contains the name of the host to which it
is connected.  Likewise, when used in the client part of an
authenticator configuration (see chapter "SMTP authentication"), $host
contains the name of the server to which the client is connected.

When used in a transport filter (see chapter "Generic options for
transports") $host refers to the host involved in the current
connection.

When a local transport is run as a result of routing a remote address,
this variable is available to access the host name that the router
defined. A router may set up many hosts; in this case $host refers to
the first one. It is expected that this usage will be mainly via the
domainlist router, setting up a single host for batched SMTP output,
for example.

$host_address: This variable is set to the remote host's IP address
whenever $host is set for a remote connection.

$host_lookup_failed: This variable contains `1' if the message came
from a remote host and there was an attempt to look up the host's name
from its IP address, but the attempt failed. Otherwise the value of the
variable is `0'.

$interface_address: For a message received over a TCP/IP connection,
this variable contains the address of the IP interface that was used.
See also the -oMi command line option.

$key: When a domain, host, or address list is being searched, this
variable contains the value of the key, so that it can be inserted into
strings for query-style lookups. See section "Use of data lookups" in
chapter "File and database lookups" for further details and an example.
In other circumstances this variable is empty.

$local_part: When an address is being directed, routed, or delivered on
its own, this variable contains the local part. If a local part prefix
or suffix has been recognized, it is not included in the value.  When a
number of addresses are being delivered in a batch by a local or remote
transport, $local_part is not set.

When a message is being delivered to a pipe, file, or autoreply
transport as a result of aliasing or forwarding, $local_part is set to
the local part of the parent address.

In all cases, all quoting is removed from the local part. For example,
for both the addresses

     "abc:xyz"@test.example
     abc\:xyz@test.example

the value of $local_part is

     abc:xyz

If you use this variable to create another address, for example, in the
"new_address" option of a "smartuser" director, you should always wrap
it inside a quoting operator:

     new_address = ${quote:$local_part}@new.domain

Because global address rewriting happens at the time a message is
received, $local_part normally contains the value after rewriting.
However, when a rewrite item is actually being processed (see chapter
"Address rewriting") $local_part contains the local part of the address
that is being rewritten; it can be used in the expansion of the
replacement address, for example, to rewrite local parts by file lookup.

$local_part_data: When a director or a router has a setting of the
"local_parts" generic option, and that involves a lookup which
succeeds, the data read by the lookup is available during the running
of the director or router as $local_part_data. In addition, if the
driver directs or routes the address to a transport, the value is
available in that transport. In all other situations, this variable
expands to nothing.

$local_part_prefix: When an address is being directed or delivered
locally, and a specific prefix for the local part was recognized, it is
available in this variable. Otherwise it is empty.

$local_part_suffix: When an address is being directed or delivered
locally, and a specific suffix for the local part was recognized, it is
available in this variable. Otherwise it is empty.

$localhost_number: This contains the expanded value of the
"localhost_number" option. The expansion happens after the main options
have been read.

$message_age: This variable is set at the start of a delivery attempt
to contain the number of seconds since the message was received. It
does not change during a single delivery attempt.

$message_body: This variable contains the initial portion of a message's
body while it is being delivered, and is intended mainly for use in
filter files. The maximum number of characters of the body that are
used is set by the "message_body_visible" configuration option; the
default is 500. Newlines are converted into spaces to make it easier to
search for phrases that might be split over a line break.

$message_body_end: This variable contains the final portion of a
message's body while it is being delivered. The format and maximum size
are as for $message_body.

$message_body_size: When a message is being received or delivered, this
variable contains the size of the body in bytes. The count starts from
the character after the blank line that separates the body from the
header.  Newlines are included in the count. See also $message_size and
$body_linecount.

$message_headers: This variable contains a concatenation of all the
header lines when a message is being processed. They are separated by
newline characters.

$message_id: When a message is being received or delivered, this
variable contains the unique message id which is used by Exim to
identify the message.

$message_precedence: When a message is being delivered, the value of any
"Precedence:" header is made available in this variable. If there is no
such header, the value is the null string.

$message_size: When a message is being received or delivered, this
variable contains its size in bytes. In most cases, the size includes
those headers that were received with the message, but not those (such
as "Envelope-to:") that are added to individual deliveries as they are
written.  However, there is one special case: during the expansion of
the "maildir_tag" option in the "appendfile" transport while doing a
delivery in maildir format, the value of $message_size is the precise
size of the file that has been written.  See also $message_body_size
and $body_linecount.

$n0 - $n9: These variables are counters that can be incremented by means
of the "add" command in filter files.

$original_domain: When a top-level address is being processed for
delivery, this contains the same value as $domain. However, if a
`child' address (for example, generated by an alias, forward, or filter
file) is being processed, this variable contains the domain of the
original address.  This differs from $parent_domain when there is more
than one level of aliasing or forwarding.  When more than one address
is being delivered in a batch by a local or remote transport,
$original_domain is not set.

Address rewriting happens as a message is received. Once it has
happened, the previous form of the address is no longer accessible. It
is the rewritten top-level address whose domain appears in this
variable.

$original_local_part: When a top-level address is being processed for
delivery, this contains the same value as $local_part. However, if a
`child' address (for example, generated by an alias, forward, or filter
file) is being processed, this variable contains the local part of the
original address.  This differs from $parent_local_part when there is
more than one level of aliasing or forwarding.  When more than one
address is being delivered in a batch by a local or remote transport,
$original_local_part is not set.

Address rewriting happens as a message is received. Once it has
happened, the previous form of the address is no longer accessible. It
is the rewritten top-level address whose local part appears in this
variable.

$originator_gid: The value of $caller_gid that was set when the message
was received. For messages received via the command line, this is the
gid of the sending user. For messages received by SMTP over TCP/IP,
this is normally the gid of the Exim user.

$originator_uid: The value of $caller_uid that was set when the message
was received. For messages received via the command line, this is the
uid of the sending user. For messages received by SMTP over TCP/IP,
this is normally the uid of the Exim user.

$parent_domain: This variable is empty, except when a `child' address
(generated by aliasing or forwarding, for example) is being processed,
in which case it contains the domain of the immediately preceding
parent address.

$parent_local_part: This variable is empty, except when a `child'
address (generated by aliasing or forwarding, for example) is being
processed, in which case it contains the local part of the immediately
preceding parent address.

$pipe_addresses: This is not an expansion variable, but is mentioned
here because the string `$pipe_addresses' is handled specially in the
command specification for the "pipe" transport and in transport
filters. It cannot be used in general expansion strings, and provokes
an `unknown variable' error if encountered.

$primary_hostname: The value set in the configuration file, or read by
the "uname()" function.

$prohibition_reason: This variable is set only during the expansion of
prohibition messages. See section "Customizing prohibition messages" in
chapter "Other policy controls on incoming mail" for details.

$qualify_domain: The value set for this option in the configuration
file.

$qualify_recipient: The value set for this option in the configuration
file, or if not set, the value of $qualify_domain.

$rbl_domain: While expanding "prohibition_message" when rejecting a
recipient because of an RBL failure (see section "Customizing
prohibition messages" in chapter "Other policy controls on incoming
mail"), $rbl_domain contains the name of the RBL domain that caused the
rejection.

$rbl_text: While expanding "prohibition_message" when rejecting a
recipient because of an RBL failure (see section "Customizing
prohibition messages" in chapter "Other policy controls on incoming
mail"), $rbl_text contains the text of a DNS TXT record that is
associated with the block, if one exists.

$received_for: If there is only a single recipient address in an
incoming message, then when the "Received:" header line is being built,
this variable contains that address. Otherwise it is empty.

$received_protocol: When a message is being processed, this variable
contains the name of the protocol by which it was received.

$recipients: This variable contains a list of envelope recipients for a
message, but is recognized only in the system filter file, to prevent
exposure of Bcc recipients to ordinary users. A comma and a space
separate the addresses in the replacement text.

$recipients_count: When a message is being processed, this variable
contains the number of envelope recipients that came with the message.
Duplicates are not excluded from the count.

$reply_address: When a message is being processed, this variable
contains the contents of the "Reply-To:" header line if one exists, or
otherwise the contents of the "From:" header line.  However, if the
message contains a set of `Resent-' header lines, their contents are
used in preference.

$return_path: When a message is being delivered, this variable contains
the return path - the sender field that will be sent as part of the
envelope. It is not enclosed in <> characters. In many cases,
$return_path has the same value as $sender_address, but if, for
example, an incoming message to a mailing list has been expanded by a
director which specifies a specific address for delivery error
messages, $return_path contains the new error address, while
$sender_address contains the original sender address that was received
with the message.

$return_size_limit: This contains the value set in the
"return_size_limit" option, rounded up to a multiple of 1000. It is
useful when a customized error message text file is in use (see chapter
"Customizing error and warning messages").

$route_option: A router may set up an arbitrary string to be passed to a
transport via this variable. Currently, only the "queryprogram" router
has the ability to do so.

$self_hostname: The generic router option "self" can be set to the
values `local' or `pass' (amongst others). These cause the address to
be passed over to the directors, as if its domain were a local domain,
or to be passed on to the next router, respectively. While subsequently
directing or routing (and doing any deliveries) $self_hostname is set
to the name of the local host that the router encountered. In other
circumstances its contents are null.

$sender_address: When a message is being processed, this variable
contains the sender's address that was received in the message's
envelope.  For delivery failure reports, the value of this variable is
the empty string.

$sender_address_domain: The domain portion of $sender_address.

$sender_address_local_part: The local part portion of $sender_address.

$sender_fullhost: When a message is received from a remote host, this
variable contains the host name and IP address in a single string,
which always ends with the IP address in square brackets.  If
"log_incoming_port" is set, the port number on the remote host is added
to the IP address, separated by a full stop.  The format of the rest of
the string depends on whether the host issued a HELO or EHLO SMTP
command, and whether the host name was verified by looking up its IP
address.  (Looking up the IP address can be forced by the "host_lookup"
option, independent of verification.)  A plain host name at the start
of the string is a verified host name; if this is not present,
verification either failed or was not requested. A host name in
parentheses is the argument of a HELO or EHLO command. This is omitted
if it is identical to the verified host name or to the host's IP
address in square brackets.

$sender_helo_name: When a message is received from a remote host that
has issued a HELO or EHLO command, the first item in the argument of
that command is placed in this variable. It is also set if HELO or EHLO
is used when a message is received using SMTP locally via the -bs or -bS
options.

$sender_host_address: When a message is received from a remote host,
this variable contains that host's IP address.  The value is set as
soon as the connection is established, so it is available, for example,
during the expansion of "prohibition_message".

$sender_host_authenticated: During message delivery, this variable
contains the name (not the public name) of the authenticator driver
which successfully authenticated the client from which the message was
received. It is empty if there was no successful authentication.

$sender_host_name: When a message is received from a remote host, this
variable contains the host's name as verified by looking up its IP
address. If verification failed, or was not requested, this variable
contains the empty string.

$sender_host_port: When a message is received from a remote host, this
variable contains the port number that was used on the remote host.

$sender_ident: When a message is received from a remote host, this
variable contains the identification received in response to an RFC
1413 request. When a message has been received locally, this variable
contains the login name of the user that called Exim.

$sender_rcvhost: This is provided specifically for use in "Received:"
headers. It starts with either the verified host name (as obtained from
a reverse DNS lookup) or, if there is no verified host name, the IP
address in square brackets. After that there may be text in
parentheses. When the first item is a verified host name, the first
thing in the parentheses is the IP address in square brackets. There
may also be items of the form `helo=xxxx' if HELO or EHLO was used and
its argument was not identical to the real host name or IP address, and
`ident=xxxx' if an RFC 1413 ident string is available. If all three
items are present in the parentheses, a newline and tab are inserted
into the string, to improve the formatting of the "Received:" header.

$sn0 - $sn9: These variables are copies of the values of the $n0 - $n9
accumulators that were current at the end of the system filter file.
This allows a system filter file to set values that can be tested in
users' filter files. For example, a system filter could set a value
indicating how likely it is that a message is junk mail.

$spool_directory: The name of Exim's spool directory.

$thisaddress: This variable is set only during the processing of the
"foranyaddress" command in a filter file. Its use is explained in the
description of that command.

$tls_cipher: When a message is received from a remote host over an
encrypted SMTP connection, this variable is set to the cipher that was
negotiated, for example DES-CBC3-SHA. See chapter "Encrypted SMTP
connections using TLS/SSL".

$tls_peerdn:  When a message is received from a remote host over an
encrypted SMTP connection, and Exim is configured to request a
certificate from the client, the value of the Distinguished Name of the
certificate is made available in the $tls_peerdn during subsequent
processing.

$tod_bsdinbox: The time of day and date, in the format required for
BSD-style mailbox files, for example: Thu Oct 17 17:14:09 1995.

$tod_full: A full version of the time and date, for example: Wed, 16 Oct
1995 09:51:40 +0100. The timezone is always given as a numerical offset
from GMT.

$tod_log: The time and date in the format used for writing Exim's log
files, for example: 1995-10-12 15:32:29.

$value: This variable contains the result of an expansion lookup or
extraction operation, as described above.  Also, if a "domainlist"
router has a lookup pattern in a route item, $value contains the data
that was looked up during the expansion of the host list.  If $value is
used in other circumstances, its contents are null.

$version_number: The version number of Exim.

$warnmsg_delay: This variable is set only during the creation of a
message warning about a delivery delay. Details of its use are
explained in section "Customizing warning messages" in chapter
"Customizing error and warning messages".

$warnmsg_recipients: This variable is set only during the creation of a
message warning about a delivery delay. Details of its use are
explained in section "Customizing warning messages" in chapter
"Customizing error and warning messages".


File: exim.info,  Node: Embedded Perl,  Next: Main configuration,  Prev: String expansions,  Up: Top

Embedded Perl
*************

Exim can be built to include an embedded Perl interpreter. When this is
done, Perl subroutines can be called as part of the string expansion
process. To make use of the Perl support, you need version 5.004 or
later of Perl installed on your system. To include the embedded
interpreter in the Exim binary, include the line

     EXIM_PERL = perl.o

in your `Local/Makefile' and then build Exim in the normal way.

Access to Perl subroutines is via a global configuration option called
"perl_startup" and an expansion string operator "${perl ...}". If there
is no "perl_startup" option in the Exim configuration file then no Perl
interpreter is started and there is almost no overhead for Exim (since
none of the Perl library will be paged in unless used). If there is a
"perl_startup" option then the associated value is taken to be Perl
code which is executed in a newly created Perl interpreter.

The value of "perl_startup" is not expanded in the Exim sense, so you
do not need backslashes before any characters to escape special
meanings. The option should usually be something like

     perl_startup = do '/etc/exim.pl'

where "/etc/exim.pl" is Perl code which defines any subroutines you
want to use from Exim. Exim can be configured either to start up a Perl
interpreter as soon as it is entered, or to wait until the first time
it is needed. Starting the interpreter at the beginning ensures that it
is done while Exim still has its setuid privilege, but can impose an
unnecessary overhead if Perl is not in fact used in a particular run.
Also, note that this does not mean that Exim is necessarily running as
root when Perl is called at a later time.  By default, the interpreter
is started only when it is needed, but this can be changed in two ways:

   * Setting "perl_at_start" (a boolean option) in the configuration
     requests a startup when Exim is entered.

   * The command line option -ps also requests a startup when Exim is
     entered, overriding the setting of "perl_at_start".

There is also a command line option -pd (for delay) which suppresses the
initial startup, even if "perl_at_start" is set.

When the configuration file includes a "perl_startup" option you can
make use of the string expansion item to call the Perl subroutines that
are defined by the "perl_startup" code. The operator is used in any of
the following forms:

     ${perl{foo}}
     ${perl{foo}{argument}}
     ${perl{foo}{argument1}{argument2} ... }

which calls the subroutine "foo" with the given arguments. A maximum of
eight arguments may be passed. Passing more than this results in an
expansion failure with an error message of the form

     Too many arguments passed to Perl subroutine "foo" (max is 8)

The return value of the subroutine is inserted into the expanded
string, unless the return value is "undef". In that case, the expansion
fails in the same way as an explicit `fail' on an "${if ...}" or
"${lookup...}" item. If the subroutine aborts by obeying Perl's "die"
function, the expansion fails with the error message that was passed to
"die".

Within any Perl code called from Exim, the function
"Exim::expand_string" is available to call back into Exim's string
expansion function. For example, the Perl code

     my $lp = Exim::expand_string('$local_part');

makes the current Exim $local_part available in the Perl variable $lp.
Note those are single quotes and not double quotes to protect against
$local_part being interpolated as a Perl variable.

If the string expansion is forced to fail by a `fail' item, the result
of "Exim::expand_string" is "undef". If there is a syntax error in the
expansion string, the Perl call from the original expansion string
fails with an appropriate error message, in the same way as if "die"
were used.


File: exim.info,  Node: Main configuration,  Next: Driver specifications,  Prev: Embedded Perl,  Up: Top

Main configuration
******************

The first part of the run time configuration file contains the main
configuration settings. Each setting occupies one line of the file,
possibly continued by a terminating backslash. If any setting is
preceded by the word `hide', the -bP option displays its value to admin
users only (see section "Common option syntax" in chapter "The Exim
configuration file").

All macro definitions must be in this part of the file - they differ
from options settings by starting with an upper-case letter (see section
"Macros in the configuration file" in chapter "The Exim configuration
file").

The available options are listed in alphabetical order below, along
with their types and default values.



* Menu:

* accept_8bitmime::
* accept_timeout::
* admin_groups::
* allow_mx_to_ip::
* always_bcc::
* auth_always_advertise::
* auth_hosts::
* auth_over_tls_hosts::
* auto_thaw::
* bi_command::
* check_log_inodes::
* check_log_space::
* check_spool_inodes::
* check_spool_space::
* collapse_source_routes::
* daemon_smtp_port::
* daemon_smtp_service::
* debug_level::
* delay_warning::
* delay_warning_condition::
* deliver_load_max::
* deliver_queue_load_max::
* delivery_date_remove::
* dns_again_means_nonexist::
* dns_check_names::
* dns_check_names_pattern::
* dns_retrans::
* dns_ipv4_lookup::
* dns_retry::
* envelope_to_remove::
* errmsg_text::
* errmsg_file::
* errors_address::
* errors_copy::
* errors_reply_to::
* exim_group::
* exim_path::
* exim_user::
* extract_addresses_remove_arguments::
* finduser_retries::
* forbid_domain_literals::
* freeze_tell_mailmaster::
* gecos_name::
* gecos_pattern::
* headers_check_syntax::
* headers_checks_fail::
* headers_sender_verify::
* headers_sender_verify_errmsg::
* helo_accept_junk_hosts::
* helo_strict_syntax::
* helo_verify::
* hold_domains::
* host_accept_relay::
* host_auth_accept_relay::
* host_lookup::
* host_reject::
* host_reject_recipients::
* hosts_treat_as_local::
* ignore_errmsg_errors::
* ignore_errmsg_errors_after::
* ignore_fromline_hosts::
* ignore_fromline_local::
* keep_malformed::
* kill_ip_options::
* ldap_default_servers::
* local_domains::
* local_domains_include_host::
* local_domains_include_host_literals::
* local_from_check::
* local_from_prefix::
* local_from_suffix::
* local_interfaces::
* localhost_number::
* locally_caseless::
* log_all_parents::
* log_arguments::
* log_file_path::
* log_incoming_port::
* log_ip_options::
* log_level::
* log_queue_run_level::
* log_received_recipients::
* log_received_sender::
* log_refused_recipients::
* log_rewrites::
* log_sender_on_delivery::
* log_smtp_confirmation::
* log_smtp_connections::
* log_smtp_syntax_errors::
* log_subject::
* lookup_open_max::
* max_username_length::
* message_body_visible::
* message_filter::
* message_filter_directory_transport::
* message_filter_directory2_transport::
* message_filter_file_transport::
* message_filter_group::
* message_filter_pipe_transport::
* message_filter_reply_transport::
* message_filter_user::
* message_id_header_text::
* message_size_limit::
* message_size_limit_count_recipients::
* move_frozen_messages::
* mysql_servers::
* never_users::
* nobody_group::
* nobody_user::
* percent_hack_domains::
* perl_at_start::
* perl_startup::
* pgsql_servers::
* pid_file_path::
* preserve_message_logs::
* primary_hostname::
* print_topbitchars::
* prod_requires_admin::
* prohibition_message::
* qualify_domain::
* qualify_recipient::
* queue_list_requires_admin::
* queue_only::
* queue_only_file::
* queue_only_load::
* queue_remote_domains::
* queue_run_in_order::
* queue_run_max::
* queue_smtp_domains::
* rbl_domains::
* rbl_hosts::
* rbl_log_headers::
* rbl_log_rcpt_count::
* rbl_reject_recipients::
* rbl_warn_header::
* received_header_text::
* received_headers_max::
* receiver_try_verify::
* receiver_unqualified_hosts::
* receiver_verify::
* receiver_verify_addresses::
* receiver_verify_hosts::
* receiver_verify_senders::
* recipients_max::
* recipients_max_reject::
* recipients_reject_except::
* recipients_reject_except_senders::
* refuse_ip_options::
* relay_domains::
* relay_domains_include_local_mx::
* relay_match_host_or_sender::
* remote_max_parallel::
* remote_sort::
* retry_data_expire::
* retry_interval_max::
* return_path_remove::
* return_size_limit::
* rfc1413_hosts::
* rfc1413_query_timeout::
* security::
* sender_address_relay::
* sender_address_relay_hosts::
* sender_reject::
* sender_reject_recipients::
* sender_try_verify::
* sender_unqualified_hosts::
* sender_verify::
* sender_verify_batch::
* sender_verify_callback_domains::
* sender_verify_callback_timeout::
* sender_verify_fixup::
* sender_verify_hosts::
* sender_verify_hosts_callback::
* sender_verify_max_retry_rate::
* sender_verify_reject::
* smtp_accept_keepalive::
* smtp_accept_max::
* smtp_accept_max_per_host::
* smtp_accept_queue::
* smtp_accept_queue_per_connection::
* smtp_accept_reserve::
* smtp_banner::
* smtp_check_spool_space::
* smtp_connect_backlog::
* smtp_etrn_command::
* smtp_etrn_hosts::
* smtp_etrn_serialize::
* smtp_expn_hosts::
* smtp_load_reserve::
* smtp_receive_timeout::
* smtp_reserve_hosts::
* smtp_verify::
* split_spool_directory::
* spool_directory::
* strip_excess_angle_brackets::
* strip_trailing_dot::
* syslog_timestamp::
* timeout_frozen_after::
* timestamps_utc::
* timezone::
* tls_advertise_hosts::
* tls_certificate::
* tls_dhparam::
* tls_host_accept_relay::
* tls_hosts::
* tls_log_cipher::
* tls_log_peerdn::
* tls_privatekey::
* tls_verify_certificates::
* tls_verify_ciphers::
* tls_verify_hosts::
* trusted_groups::
* trusted_users::
* unknown_login::
* unknown_username::
* untrusted_set_sender::
* uucp_from_pattern::
* uucp_from_sender::
* warnmsg_file::


File: exim.info,  Node: accept_8bitmime,  Next: accept_timeout,  Prev: Main configuration,  Up: Main configuration

accept_8bitmime _option_
------------------------

Type: boolean
Default: false

This option causes Exim to send 8BITMIME in its response to an SMTP
EHLO command, and to accept the BODY= parameter on MAIL commands.
However, though Exim is 8-bit clean, it is not a protocol converter,
and it takes no steps to do anything special with messages received by
this route. Consequently, this option is turned off by default.


File: exim.info,  Node: accept_timeout,  Next: admin_groups,  Prev: accept_8bitmime,  Up: Main configuration

accept_timeout _option_
-----------------------

Type: time
Default: 0s

This sets the timeout for accepting a non-SMTP message, that is, the
maximum time that Exim waits when reading a message on the standard
input. If the value is zero, it will wait for ever. This setting is
overridden by the -or command option.  The timeout for incoming SMTP
messages is controlled by "smtp_receive_timeout".


File: exim.info,  Node: admin_groups,  Next: allow_mx_to_ip,  Prev: accept_timeout,  Up: Main configuration

admin_groups _option_
---------------------

Type: string list
Default: unset

If the current group or any of the supplementary groups of the caller
is in this list, the caller has admin privileges. If all your system
programmers are in a specific group, for example, you can give them all
Exim admin privileges by putting that group in "admin_groups".
However, this does not permit them to read Exim's spool files (whose
group owner is the Exim gid). To permit this, you have to add
individuals to the Exim group.


File: exim.info,  Node: allow_mx_to_ip,  Next: always_bcc,  Prev: admin_groups,  Up: Main configuration

allow_mx_to_ip _option_
-----------------------

Type: boolean
Default: false

It appears that more and more DNS zones are breaking the rules and
putting IP addresses on the right hand side of MX records. Exim follows
the rules and rejects this, giving an error message that explains the
mis-configuration.  However, some other MTAs support this practice, so
to avoid `Why can't Exim do this?' complaints, "allow_mx_to_ip" exists,
in order to enable this heinous activity. It is not recommended, except
when you have no other choice.


File: exim.info,  Node: always_bcc,  Next: auth_always_advertise,  Prev: allow_mx_to_ip,  Up: Main configuration

always_bcc _option_
-------------------

Type: boolean
Default: false

Exim adds a "To:" header to messages whose recipients are given on the
command line when there is no "To:", "Cc:", or "Bcc:" in the message.
In other cases of missing recipient headers, it just adds an empty
"Bcc:" header to make the message conform with RFC 822. Setting
"always_bcc" causes it to add an empty "Bcc:" in all cases. This can be
helpful in conjunction with mailing list software that passes recipient
addresses on the command line.


File: exim.info,  Node: auth_always_advertise,  Next: auth_hosts,  Prev: always_bcc,  Up: Main configuration

auth_always_advertise _option_
------------------------------

Type: boolean
Default: true

This option is available only when Exim is compiled with authentication
support. Normally, if any server authentication mechanisms are
configured, Exim advertises them in response to any EHLO command.
However, if "auth_always_advertise" is set false, Exim advertises
availability of the AUTH command only if the calling host is in
"auth_hosts", or if it is in "host_auth_accept_relay" and not in
"host_accept_relay". In other words, it advertises only when the host is
required always to authenticate or to authenticate in order to relay.

Otherwise, Exim does not advertise AUTH, though it is always prepared to
accept it. Certain mail clients (for example, Netscape) require the
user to provide a name and password for authentication if AUTH is
advertised, even though it may not be needed (the host may be in
"host_accept_relay").  Unsetting "auth_always_advertise" makes these
clients more friendly in these circumstances, while still allowing you
to use combinations such as

     host_auth_accept_relay = *
     host_accept_relay = 10.9.8.0/24

without needing to fill up "host_auth_accept_relay" with exceptions.


File: exim.info,  Node: auth_hosts,  Next: auth_over_tls_hosts,  Prev: auth_always_advertise,  Up: Main configuration

auth_hosts _option_
-------------------

Type: host list
Default: unset

Any hosts in this list that connect to an Exim server as clients are
required to authenticate themselves using the SMTP AUTH command before
any commands other than HELO, EHLO, HELP, AUTH, NOOP, RSET, or QUIT are
accepted. See chapter "SMTP authentication" for details of SMTP
authentication.


File: exim.info,  Node: auth_over_tls_hosts,  Next: auto_thaw,  Prev: auth_hosts,  Up: Main configuration

auth_over_tls_hosts _option_
----------------------------

Type: host list
Default: unset

Any hosts in this list must start an encrypted TLS session before
issuing an SMTP AUTH command, but it does not of itself require them to
authenticate.  See chapter "Encrypted SMTP connections using TLS/SSL"
for details of SMTP encryption.


File: exim.info,  Node: auto_thaw,  Next: bi_command,  Prev: auth_over_tls_hosts,  Up: Main configuration

auto_thaw _option_
------------------

Type: time
Default: 0s

If this option is set to a time greater than zero, a queue runner will
try a new delivery attempt on any frozen message if this much time has
passed since it was frozen. This may result in the message being
re-frozen if nothing has changed since the last attempt. It is a way of
saying `keep on trying, even though there are big problems'. See also
"timeout_frozen_after", "ignore_errmsg_errors", and
"ignore_errmsg_errors_after".


File: exim.info,  Node: bi_command,  Next: check_log_inodes,  Prev: auto_thaw,  Up: Main configuration

bi_command _option_
-------------------

Type: string
Default: unset

This option supplies the name of a command that is run when Exim is
called with the -bi option (see chapter "The Exim command line"). The
string value is just the command name, it is not a complete command
line. If an argument is required, it must come from the -oA command
line option.


File: exim.info,  Node: check_log_inodes,  Next: check_log_space,  Prev: bi_command,  Up: Main configuration

check_log_inodes _option_
-------------------------

Type: integer
Default: 0

See "check_spool_space" below.


File: exim.info,  Node: check_log_space,  Next: check_spool_inodes,  Prev: check_log_inodes,  Up: Main configuration

check_log_space _option_
------------------------

Type: integer
Default: 0

See "check_spool_space" below.


File: exim.info,  Node: check_spool_inodes,  Next: check_spool_space,  Prev: check_log_space,  Up: Main configuration

check_spool_inodes _option_
---------------------------

Type: integer
Default: 0

See "check_spool_space" below.


File: exim.info,  Node: check_spool_space,  Next: collapse_source_routes,  Prev: check_spool_inodes,  Up: Main configuration

check_spool_space _option_
--------------------------

Type: integer
Default: 0

The four "check_..." options allow for checking of disc resources
before a message is accepted: "check_spool_space" and
"check_spool_inodes" check the spool partition if either value is
greater than zero, for example:

     check_spool_space = 10M
     check_spool_inodes = 100

The spool partition is the one which contains the directory defined by
SPOOL_DIRECTORY in `Local/Makefile'.

"check_log_space" and "check_log_inodes"  check the partition in which
log files are written if either is greater than zero. These should be
set only if "log_file_path" and "spool_directory" refer to different
partitions.

If there is less space or fewer inodes than requested, Exim refuses to
accept incoming mail. In the case of SMTP input this is done by giving
a 452 temporary error response to the MAIL command. If ESMTP is in use
and there was a SIZE parameter on the MAIL command, its value is added
to the "check_spool_space" value, and the check is performed even if
"check_spool_space" is zero, unless "no_smtp_check_spool_space" is set.

For non-SMTP input and for batched SMTP input, the test is done at
start-up; on failure a message is written to stderr and Exim exits with
a non-zero code, as it obviously cannot send an error message of any
kind.


File: exim.info,  Node: collapse_source_routes,  Next: daemon_smtp_port,  Prev: check_spool_space,  Up: Main configuration

collapse_source_routes _option_
-------------------------------

Type: boolean
Default: false

From version 3.10, this option is obsolete and does nothing. Formerly,
it caused source-routed mail addresses to be stripped down to their
final components. This now happens automatically, and cannot be
suppressed.


File: exim.info,  Node: daemon_smtp_port,  Next: daemon_smtp_service,  Prev: collapse_source_routes,  Up: Main configuration

daemon_smtp_port _option_
-------------------------

Type: string
Default: unset

This option specifies the numerical port number or the service name
equivalent on which the daemon is to listen for incoming SMTP calls. It
is overridden by -oX on the command line. If this option is not set,
the service name `smtp' is used.


File: exim.info,  Node: daemon_smtp_service,  Next: debug_level,  Prev: daemon_smtp_port,  Up: Main configuration

daemon_smtp_service _option_
----------------------------

Type: string
Default: unset

This option is a synonym for "daemon_smtp_port".


File: exim.info,  Node: debug_level,  Next: delay_warning,  Prev: daemon_smtp_service,  Up: Main configuration

debug_level _option_
--------------------

Type: integer
Default: 0

This option sets the debug level, thus enabling it to be set when
calling Exim from an MUA, but it is overridden by the use of -d on the
command line.


File: exim.info,  Node: delay_warning,  Next: delay_warning_condition,  Prev: debug_level,  Up: Main configuration

delay_warning _option_
----------------------

Type: time list
Default: 24h

When a message is delayed, Exim sends a warning message to the sender at
intervals specified by this option. If it is set to a zero, no warnings
are sent. The data is a colon-separated list of times after which to
send warning messages. Up to 10 times may be given. If a message has
been on the queue for longer than the last time, the last interval
between the times is used to compute subsequent warning times. For
example, with

     delay_warning = 4h:8h:24h

the first message is sent after 4 hours, the second after 8 hours, and
subsequent ones every 16 hours thereafter. To stop warnings after a
given time, set a huge subsequent time.


File: exim.info,  Node: delay_warning_condition,  Next: deliver_load_max,  Prev: delay_warning,  Up: Main configuration

delay_warning_condition _option_
--------------------------------

Type: string, expanded
Default: see below

The string is expanded at the time a warning message might be sent. If
all the deferred addresses have the same domain, it is set in $domain
during the expansion. Otherwise $domain is empty. If the result of the
expansion is a forced failure, an empty string, or a string matching
any of `0', `no' or `false' (the comparison being done caselessly) then
the warning message is not sent. The default is

     delay_warning_condition = \
       ${if match{$h_precedence:}{(?i)bulk|list|junk}{no}{yes}}

which suppresses the sending of warnings about messages that have
`bulk', `list' or `junk' in a "Precedence:" header. Note that the colon
to terminate the header name cannot be omitted, because brace
characters may legally occur in header names.


File: exim.info,  Node: deliver_load_max,  Next: deliver_queue_load_max,  Prev: delay_warning_condition,  Up: Main configuration

deliver_load_max _option_
-------------------------

Type: fixed-point
Default: unset

When this option is set, no message deliveries are ever done if the
system load average is greater than its value, except for deliveries
forced with the -M option.  If "deliver_queue_load_max" is not set and
the load gets this high during a queue run, the run is abandoned.
There are some operating systems for which Exim cannot determine the
load average (see chapter 1); for these this option has no effect.


File: exim.info,  Node: deliver_queue_load_max,  Next: delivery_date_remove,  Prev: deliver_load_max,  Up: Main configuration

deliver_queue_load_max _option_
-------------------------------

Type: fixed-point
Default: unset

If this option is set, its value is used to determine whether to
abandon a queue run, instead of the value of "deliver_load_max".


File: exim.info,  Node: delivery_date_remove,  Next: dns_again_means_nonexist,  Prev: deliver_queue_load_max,  Up: Main configuration

delivery_date_remove _option_
-----------------------------

Type: boolean
Default: true

Exim's transports have an option for adding a "Delivery-date:" header
to a message when it is delivered - in exactly the same way as
"Return-path:" is handled. "Delivery-date:" records the actual time of
delivery. Such headers should not be present in incoming messages, and
this option causes them to be removed, to avoid any problems that might
occur when a delivered message is subsequently sent on to some other
recipient.


File: exim.info,  Node: dns_again_means_nonexist,  Next: dns_check_names,  Prev: delivery_date_remove,  Up: Main configuration

dns_again_means_nonexist _option_
---------------------------------

Type: domain list
Default: unset

DNS lookups give a `try again' response for the DNS error
`non-Authoritive host found or SERVERFAIL'. This can cause Exim to keep
trying to deliver a message, or to give repeated temporary errors to
incoming mail. Sometimes the effect is caused by a badly set up
nameserver and may persist for a long time.  If a domain which exhibits
this problem matches anything in "dns_again_means_nonexist" then it is
treated as if it did not exist. This option should be used with care.


File: exim.info,  Node: dns_check_names,  Next: dns_check_names_pattern,  Prev: dns_again_means_nonexist,  Up: Main configuration

dns_check_names _option_
------------------------

Type: boolean
Default: true

This option causes Exim to check domain names for illegal characters
before handing them to the DNS resolver, because some resolvers give
temporary errors for bad names. If a domain name contains any illegal
characters, a `not found' result is forced.  The check is done by
matching the domain name against the regular expression specified by
the "dns_check_names_pattern" option.


File: exim.info,  Node: dns_check_names_pattern,  Next: dns_retrans,  Prev: dns_check_names,  Up: Main configuration

dns_check_names_pattern _option_
--------------------------------

Type: string
Default: see below

This option defines the regular expression that is used when the
"dns_check_names" option is set. The default value is

     dns_check_names_pattern = \
       (?i)^(?>(?(1)\.|())[^\W_](?>[a-z0-9-]*[^\W_])?)+$

which permits only letters, digits, and hyphens in components, but they
may not start or end with a hyphen.


File: exim.info,  Node: dns_retrans,  Next: dns_ipv4_lookup,  Prev: dns_check_names_pattern,  Up: Main configuration

dns_retrans _option_
--------------------

Type: time
Default: 0s

The options "dns_retrans" and "dns_retry" can be used to set the
retransmission and retry parameters for DNS lookups. Values of zero (the
defaults) leave the system default settings unchanged. The first value
is the time between retries, and the second is the number of retries.
It isn't totally clear exactly how these settings affect the total time
a DNS lookup may take. I haven't found any documentation about timeouts
on DNS lookups; these parameter values are available in the external
resolver interface structure, but nowhere does it seem to describe how
they are used or what you might want to set in them.


File: exim.info,  Node: dns_ipv4_lookup,  Next: dns_retry,  Prev: dns_retrans,  Up: Main configuration

dns_ipv4_lookup _option_
------------------------

Type: boolean
Default: false

When Exim is compiled with IPv6 support, it looks for IPv6 address
records (AAAA and A6) as well as IPv4 address records when trying to
find IP addresses for hosts. However, if "dns_ipv4_lookup" is set, it
disables DNS lookups for AAAA and A6 records. This is a fudge to help
with name servers that give big delays or otherwise do not work for
these new record types. If Exim is handed either of these record types
as part of an MX lookup (for example), it still handles them, and may
as a result make outgoing IPv6 calls. All this option does is to make
it look only for IPv4-style A records when it needs to find an IP
address for a host name. In due course, when the world's name servers
have all been upgraded, there should be no need for this option.


File: exim.info,  Node: dns_retry,  Next: envelope_to_remove,  Prev: dns_ipv4_lookup,  Up: Main configuration

dns_retry _option_
------------------

Type: integer
Default: 0

See "dns_retrans" above.


File: exim.info,  Node: envelope_to_remove,  Next: errmsg_text,  Prev: dns_retry,  Up: Main configuration

envelope_to_remove _option_
---------------------------

Type: boolean
Default: true

Exim's transports have an option for adding an "Envelope-to:" header to
a message when it is delivered - in exactly the same way as
"Return-path:" is handled. "Envelope-to:" records the original recipient
address in the envelope that caused the delivery. Such headers should
not be present in incoming messages, and this option causes them to be
removed, to avoid any problems that might occur when a delivered
message is subsequently sent on to some other recipient.


File: exim.info,  Node: errmsg_text,  Next: errmsg_file,  Prev: envelope_to_remove,  Up: Main configuration

errmsg_text _option_
--------------------

Type: string
Default: unset

If "errmsg_text" is set, its contents are included in the default error
message immediately after `This message was created automatically by
mail delivery software.' It is not used if "errmsg_file" is set.


File: exim.info,  Node: errmsg_file,  Next: errors_address,  Prev: errmsg_text,  Up: Main configuration

errmsg_file _option_
--------------------

Type: string
Default: unset

This option defines a template file containing paragraphs of text to be
used for constructing the message which is sent by Exim in the case of a
delivery failure. Details of the file's contents are given in chapter
"Customizing error and warning messages". See also "warnmsg_file".


File: exim.info,  Node: errors_address,  Next: errors_copy,  Prev: errmsg_file,  Up: Main configuration

errors_address _option_
-----------------------

Type: string
Default: "postmaster"

The mail address to which Exim will send certain error reports. As the
default is specified without a domain, it will be sent to the domain
specified by the "qualify_recipient" option. If this address is
specified with a domain, it must be a fully qualified domain.  There
are actually only a few situations where this address is used:

   * When "freeze_tell_mailmaster" is set, and a message that is not a
     failing, locally generated bounce message is frozen. However, if
     the "errors_address" is one of the recipients of the frozen
     message, nothing is sent, in order to avoid potential loops.

   * Delivery failed, and there is no other address to which a bounce
     message can be sent, except for bounce messages that are timing
     out (they are just discarded).

   * -Mg was used to cancel delivery, and there is no other address to
     which to send a message.


File: exim.info,  Node: errors_copy,  Next: errors_reply_to,  Prev: errors_address,  Up: Main configuration

errors_copy _option_
--------------------

Type: string list, expanded
Default: unset

Setting this option causes Exim to send bcc copies of delivery failure
reports that it generates to other addresses. The value is a
colon-separated list of items; each item consists of a pattern and an
address list, separated by white space. If the pattern matches the
recipient of the delivery error report, the message is copied to the
addresses on the list. The items are scanned in order, and once a
matching one is found, no further items are examined. For example:

     errors_copy = spqr@mydomain   postmaster@mydomain :\
                   rqps@mydomain   mailmaster@mydomain,\
                                   postmaster@mydomain

Each pattern can be a single regular expression, indicated by starting
it with a circumflex; alternatively, either portion (local part,
domain) can start with an asterisk, or the domain can be in any format
that is acceptable as an item in a domain list, including a file
lookup. A regular expression is matched against the entire (fully
qualified) recipient; non-regular expressions must contain both a local
part and domain, separated by @.

The address list is a string which is expanded, and must end up as a
comma-separated list of addresses. It is used to construct a "Bcc:"
header which is added to the error message. The expansion variables
$local_part and $domain are set from the original recipient of the
error message, and if there was any wildcard matching, the expansion
variables $0, $1, etc. are set in the normal way.


File: exim.info,  Node: errors_reply_to,  Next: exim_group,  Prev: errors_copy,  Up: Main configuration

errors_reply_to _option_
------------------------

Type: string
Default: unset

Exim's delivery error messages contain the header

     From: Mail Delivery System <Mailer-Daemon@${qualify_domain}>

(where string expansion notation is used to show a variable
substitution).  Experience shows that a large number of people reply to
such messages. If the "errors_reply_to" option is set, a "Reply-To:"
header is added. The option must specify the complete header body.


File: exim.info,  Node: exim_group,  Next: exim_path,  Prev: errors_reply_to,  Up: Main configuration

exim_group _option_
-------------------

Type: string
Default: compile-time configured (can be unset)

This option sets the gid under which Exim runs when it gives up root
privilege.  It is used only when "exim_user" is also set. Unless it
consists entirely of digits, the string is looked up using
"getgrnam()", and failure causes a configuration error. See chapter
"Security considerations" for a discussion of security issues.


File: exim.info,  Node: exim_path,  Next: exim_user,  Prev: exim_group,  Up: Main configuration

exim_path _option_
------------------

Type: string
Default: see below

This option specifies the path name of the Exim binary, which is used
when Exim needs to re-exec itself. The default is set up to point to
the file "exim" in the directory configured at compile time by the
BIN_DIRECTORY setting. It is necessary to change "exim_path" if Exim is
run from some other place.


File: exim.info,  Node: exim_user,  Next: extract_addresses_remove_arguments,  Prev: exim_path,  Up: Main configuration

exim_user _option_
------------------

Type: string
Default: compile-time configured (can be unset)

This option sets the uid under which Exim runs when it gives up root
privilege.  However, unless there is some compelling reason for not
doing so, it is best to specify the uid by setting EXIM_UID in
`Local/Makefile' rather than using this option, because ownership of
the run time configuration file and the use of the -C and -D command
line options is checked against the compile-time setting of this
parameter, not what is set here.

Unless it consists entirely of digits, the string is looked up using
"getpwnam()", and failure causes a configuration error. If "exim_group"
is not also supplied, the gid is taken from the result of "getpwnam()"
if it is used.  If the resulting uid is the root uid, it has the effect
of unsetting this option. See chapter "Security considerations" for a
discussion of security issues.


File: exim.info,  Node: extract_addresses_remove_arguments,  Next: finduser_retries,  Prev: exim_user,  Up: Main configuration

extract_addresses_remove_arguments _option_
-------------------------------------------

Type: boolean
Default: true

According to Sendmail documentation, if any addresses are present on the
command line when the -t option is used to build an envelope from a
message's headers, they are removed from the recipients list. This is
also how Smail behaves. However, it has been reported that some
versions of Sendmail in fact add the argument addresses to the
recipients list. By default Exim follows the documented behaviour, but
if this option is set false it adds rather than removes argument
addresses.


File: exim.info,  Node: finduser_retries,  Next: forbid_domain_literals,  Prev: extract_addresses_remove_arguments,  Up: Main configuration

finduser_retries _option_
-------------------------

Type: integer
Default: 0

On systems running NIS or other schemes in which user and group
information is distributed from a remote system, there can be times
when "getpwnam()" and related functions fail, even when given valid
data, because things time out.  Unfortunately these failures cannot be
distinguished from genuine `not found' errors. If "finduser_retries" is
set greater than zero, Exim will try that many extra times to find a
user or a group, waiting for one second between tries.


File: exim.info,  Node: forbid_domain_literals,  Next: freeze_tell_mailmaster,  Prev: finduser_retries,  Up: Main configuration

forbid_domain_literals _option_
-------------------------------

Type: boolean
Default: false

If this option is set, the RFC 822 domain literal format is not
permitted in addresses.  The option is set in the default configuration
file, because the domain literal format is not normally required these
days, and few people know about it.  It has, however, been exploited by
mail abusers.


File: exim.info,  Node: freeze_tell_mailmaster,  Next: gecos_name,  Prev: forbid_domain_literals,  Up: Main configuration

freeze_tell_mailmaster _option_
-------------------------------

Type: boolean
Default: false

On encountering certain errors, Exim freezes a message, which means
that no further delivery attempts take place until an administrator
thaws it. If this option is set, a message is sent to "errors_address"
every time a message is frozen, unless the message is itself a delivery
error message. (Without this exception there is the possibility of
looping.)  If several of the message's addresses cause freezing, only a
single message is sent to the mail administrator. The reason(s) for
freezing will be found in the message log.


File: exim.info,  Node: gecos_name,  Next: gecos_pattern,  Prev: freeze_tell_mailmaster,  Up: Main configuration

gecos_name _option_
-------------------

Type: string, expanded
Default: unset

Some operating systems, notably HP-UX, use the `gecos' field in the
system password file to hold other information in addition to users'
real names. Exim looks up this field for use when it is creating
"Sender:" or "From:" headers. If either "gecos_pattern" or "gecos_name"
are unset, the contents of the field are used unchanged, except that,
if an ampersand is encountered, it is replaced by the user's login name
with the first character forced to upper-case, since this is a
convention that is observed on many systems.

When these options are set, "gecos_pattern" is treated as a regular
expression that is to be applied to the field (again with & replaced by
the login name), and if it matches, "gecos_name" is expanded and used
as the user's name.  Numeric variables such as $1, $2, etc. can be used
in the expansion to pick up sub-fields that were matched by the
pattern. In HP-UX, where the user's name terminates at the first comma,
the following can be used:

     gecos_pattern = ([^,]*)
     gecos_name = $1


File: exim.info,  Node: gecos_pattern,  Next: headers_check_syntax,  Prev: gecos_name,  Up: Main configuration

gecos_pattern _option_
----------------------

Type: string
Default: unset

See "gecos_name" above.


File: exim.info,  Node: headers_check_syntax,  Next: headers_checks_fail,  Prev: gecos_pattern,  Up: Main configuration

headers_check_syntax _option_
-----------------------------

Type: boolean
Default: false

This option causes Exim to check the syntax of all headers that can
contain lists of addresses ("Sender:", "From:", "Reply-To:", "To:",
"Cc:", and "Bcc:") on all incoming messages (both local and SMTP). This
is a syntax check only, to catch real junk such as

     To: user@

Like the "headers_sender_verify" options, the rejection happens after
the end of the data, but it is also controlled by
"headers_checks_fail"; if that is unset, the message is accepted and a
warning is written to the reject log.

If the message contains any headers starting with `Resent-' then it is
that set of headers which is checked.


File: exim.info,  Node: headers_checks_fail,  Next: headers_sender_verify,  Prev: headers_check_syntax,  Up: Main configuration

headers_checks_fail _option_
----------------------------

Type: boolean
Default: true

If this option is true, failure of any header check (see below) causes
the message to be rejected. If it is false, a warning message is
written to the reject log.


File: exim.info,  Node: headers_sender_verify,  Next: headers_sender_verify_errmsg,  Prev: headers_checks_fail,  Up: Main configuration

headers_sender_verify _option_
------------------------------

Type: boolean
Default: false

If this option is set with "sender_verify", and the sending host
matches "sender_verify_hosts", Exim insists on there being at least one
verifyable address in one of the "Sender:", "Reply-To:", or "From:"
headers (which are checked in that order) on all incoming SMTP
messages. If one cannot be found, the message is rejected, unless
"headers_checks_fail" is unset, in which case a warning entry is
written to the reject log.

If there are any headers whose names start with `Resent-', it is that
set of headers which is checked. If there is more than one instance of
a particular header, all of them are checked.

Unfortunately, because it has to read the message before doing this
check, the rejection happens after the end of the data, and it is known
that some mailers do not treat hard (5xx) errors correctly at this
point - they keep the message on their spools and try again later, but
that is their problem, though it does waste some resources.


File: exim.info,  Node: headers_sender_verify_errmsg,  Next: helo_accept_junk_hosts,  Prev: headers_sender_verify,  Up: Main configuration

headers_sender_verify_errmsg _option_
-------------------------------------

Type: boolean
Default: false

This option acts like "headers_sender_verify", except that it applies
only to messages whose envelope sender is `<>', that is, delivery error
messages whose sender cannot be verified at the time the SMTP MAIL
command is received.


File: exim.info,  Node: helo_accept_junk_hosts,  Next: helo_strict_syntax,  Prev: headers_sender_verify_errmsg,  Up: Main configuration

helo_accept_junk_hosts _option_
-------------------------------

Type: host list
Default: unset

Exim checks the syntax of HELO and EHLO commands for incoming SMTP
mail, and gives an error response for invalid data. Unfortunately,
there are some SMTP clients that send syntactic junk. They can be
accommodated by setting this option.


File: exim.info,  Node: helo_strict_syntax,  Next: helo_verify,  Prev: helo_accept_junk_hosts,  Up: Main configuration

helo_strict_syntax _option_
---------------------------

Type: boolean
Default: false

Because so many systems have been found to use underscores in the names
they send in the SMTP HELO command, Exim by default permits them,
though it is not in fact legal to use underscores in domain names in
SMTP.  If "helo_strict_syntax" is set, underscores are not permitted in
HELO or EHLO commands.


File: exim.info,  Node: helo_verify,  Next: hold_domains,  Prev: helo_strict_syntax,  Up: Main configuration

helo_verify _option_
--------------------

Type: host list
Default: unset

The RFCs mandate that a server must not reject a message because it
doesn't like the HELO or EHLO command. However, some sites like to be
stricter.  If "helo_verify" is set, Exim checks each incoming call from
any host that matches it, and accepts the call only if:

   * A HELO or EHLO command is received;

and

   * The host name given in that command either:

       a. is an IP literal matching the calling address of the host
          (the RFCs specifically allow this), or

       b. matches the host name that Exim obtains by doing a reverse
          lookup of the calling host address, or

       c. when looked up using "gethostbyname()" yields the calling
          host address.


If no HELO or EHLO is given, MAIL commands are rejected; if a bad HELO
or EHLO is given, it is rejected with a 550 error. Rejections are
logged in the main and reject logs.


File: exim.info,  Node: hold_domains,  Next: host_accept_relay,  Prev: helo_verify,  Up: Main configuration

hold_domains _option_
---------------------

Type: domain list
Default: unset

This option allows mail for particular domains to be held on the queue
manually. The option is overridden if a message delivery is forced with
the -M, -qf, -Rf or -Sf options. Otherwise, if a domain matches an item
in "hold_domains", no routing or delivery for that address is done, and
it is deferred every time the message is looked at.

This option is intended as a temporary operational measure for delaying
the delivery of mail while some problem is being sorted out, or some new
configuration tested. It does not override Exim's message clearing away
code, which removes messages from the queue if they have been there
longer than the longest retry time in any retry rule. If you want to
hold messages for longer than the normal retry times, insert a dummy
retry rule with a long retry time.


File: exim.info,  Node: host_accept_relay,  Next: host_auth_accept_relay,  Prev: hold_domains,  Up: Main configuration

host_accept_relay _option_
--------------------------

Type: host list
Default: unset

This option provides a list of hosts that are permitted to relay via
the local host to any arbitrary domains. Section "Control of relaying"
in chapter "Other policy controls on incoming mail" contains a
discussion of relay control.


File: exim.info,  Node: host_auth_accept_relay,  Next: host_lookup,  Prev: host_accept_relay,  Up: Main configuration

host_auth_accept_relay _option_
-------------------------------

Type: host list
Default: unset 7

This option provides a list of hosts that are permitted to relay via
the local host to any arbitrary domains, provided the calling host has
authenticated itself. Section "Control of relaying" in chapter "Other
policy controls on incoming mail" contains a discussion of relay
control, and chapter "SMTP authentication" discusses authentication.


File: exim.info,  Node: host_lookup,  Next: host_reject,  Prev: host_auth_accept_relay,  Up: Main configuration

host_lookup _option_
--------------------

Type: host list
Default: unset

Exim does not look up the name of a calling host from its IP address
unless it is required to compare against some host list, or
"helo_verify" is set, or the address matches this option (which
normally contains IP addresses rather than host names, since the
presence of names in itself implies a DNS lookup). The default
configuration file contains

     host_lookup = *

which causes a lookup to happen for all hosts. If the expense of these
lookups is felt to be too great, the setting can be changed or removed.
However, Exim always does a lookup if the domain name quoted in a HELO
or EHLO command is the local host's own name or any of its local mail
domains.


File: exim.info,  Node: host_reject,  Next: host_reject_recipients,  Prev: host_lookup,  Up: Main configuration

host_reject _option_
--------------------

Type: host list
Default: unset

If this option is set, incoming SMTP calls from the hosts listed
(possibly also qualified by an RFC 1413 identification) are rejected as
soon as the connection is made. See chapter "Other policy controls on
incoming mail" for more details.


File: exim.info,  Node: host_reject_recipients,  Next: hosts_treat_as_local,  Prev: host_reject,  Up: Main configuration

host_reject_recipients _option_
-------------------------------

Type: host list
Default: unset

If this option is set, all recipients in incoming SMTP calls from the
hosts listed, possibly also qualified by an RFC 1413 identification,
are rejected.  Chapter "Other policy controls on incoming mail"
contains details of this facility, which differs from "host_reject"
only in the point in the SMTP dialogue at which the rejection occurs.


File: exim.info,  Node: hosts_treat_as_local,  Next: ignore_errmsg_errors,  Prev: host_reject_recipients,  Up: Main configuration

hosts_treat_as_local _option_
-----------------------------

Type: domain list
Default: unset

If this option is set, any host names that match the domain list are
treated as if they were the local host when Exim is scanning host lists
obtained from MX records, and also at other times when it is checking
whether a host to which a message has been routed is the local host. If
it is required that the matching host names also be treated as local
domains for mail delivery, they must appear in "local_domains" as well
as in this option.

See also the "allow_localhost" option in the "smtp" transport. Both
these options are needed in a setup with different hosts for incoming
and outgoing mail if the resulting system is used for MX backup.


File: exim.info,  Node: ignore_errmsg_errors,  Next: ignore_errmsg_errors_after,  Prev: hosts_treat_as_local,  Up: Main configuration

ignore_errmsg_errors _option_
-----------------------------

Type: boolean
Default: false

If this option is set, failed addresses in error reports (that is,
bounce messages, whose senders are `<>') are discarded (with a log
entry). The default action is to freeze such messages for human
attention.


File: exim.info,  Node: ignore_errmsg_errors_after,  Next: ignore_fromline_hosts,  Prev: ignore_errmsg_errors,  Up: Main configuration

ignore_errmsg_errors_after _option_
-----------------------------------

Type: time
Default: 0s

This option, if it is set to a non-zero time, acts as a delayed version
of "ignore_errmsg_errors", which must be unset for this option to take
effect.  When an error message that was frozen because of delivery
failure has been on the queue for more than the given time, it is
unfrozen at the next queue run, and a further delivery is attempted. If
delivery fails again, the error message is discarded. This makes it
possible to keep failed error messages around for a shorter time than
the normal maximum retry time for frozen messages. For example,

     ignore_errmsg_errors_after = 12h

retries failed error message deliveries after 12 hours, discarding any
further failures. For ways of automatically dealing with other kinds of
frozen message, see "auto_thaw" and "timeout_frozen_after".


File: exim.info,  Node: ignore_fromline_hosts,  Next: ignore_fromline_local,  Prev: ignore_errmsg_errors_after,  Up: Main configuration

ignore_fromline_hosts _option_
------------------------------

Type: host list
Default: unset

Some broken SMTP clients insist on sending a UUCP-like `From' line
before the headers of a message. By default this is treated as the
start of the message's body, which means that any following headers are
not recognized as such. Exim can be made to ignore it by setting
"ignore_fromline_hosts" to match those hosts that insist on sending it.
If the sender is actually a local process rather than a remote host,
and is using -bs to inject the messages, "ignore_fromline_local" can be
set to deal with this case.


File: exim.info,  Node: ignore_fromline_local,  Next: keep_malformed,  Prev: ignore_fromline_hosts,  Up: Main configuration

ignore_fromline_local _option_
------------------------------

Type: boolean
Default: false

See "ignore_fromline_hosts" above.


File: exim.info,  Node: keep_malformed,  Next: kill_ip_options,  Prev: ignore_fromline_local,  Up: Main configuration

keep_malformed _option_
-----------------------

Type: time
Default: 4d

This option specifies the length of time to keep messages whose spool
files have been corrupted in some way. This should, of course, never
happen. At the next attempt to deliver such a message, it gets removed.
The incident is logged.


File: exim.info,  Node: kill_ip_options,  Next: ldap_default_servers,  Prev: keep_malformed,  Up: Main configuration

kill_ip_options _option_
------------------------

Type: boolean
Default: true

IP packets can contain options which are "source routing" data that
enables one host to pretend to be another. (Don't confuse IP source
routing with source-routed mail addresses, which are something entirely
different.)  IP source routing is an obvious security risk, and many
sites lock out such packets in their routers. Also, some operating
systems are able to disable IP source routing at the kernel level.

If Exim receives an SMTP call with IP options set, it logs the options
if "log_ip_options" is set. Then, if "refuse_ip_options" is set, it
drops the call; otherwise, if "kill_ip_options" is set, it unsets the
options on the outgoing socket and attempts to continue.  To read the
IP options, "getsockopt()" is used. On some versions of SunOS 4.1 this
causes system crashes. There is a patch that fixes this problem, but it
can be avoided by setting all three Exim options false.


File: exim.info,  Node: ldap_default_servers,  Next: local_domains,  Prev: kill_ip_options,  Up: Main configuration

ldap_default_servers _option_
-----------------------------

Type: string list
Default: unset

This option provides a list of LDAP servers which are tried in turn
when an LDAP query does not contain a server. See section "More about
LDAP" in chapter "File and database lookups". The option is available
only when Exim has been built with LDAP support.


File: exim.info,  Node: local_domains,  Next: local_domains_include_host,  Prev: ldap_default_servers,  Up: Main configuration

local_domains _option_
----------------------

Type: domain list
Default: see below

This specifies a list of domains which are recognized as `local', that
is, their delivery is handled in a special way by this MTA using
directors rather than routers.  If this option is not set, it defaults
to the value of "qualify_recipient".

The name of the local host is not by default recognized as a local mail
domain; either it must be included in "local_domains", or the
"local_domains_include_host" option must be set.  If you want to accept
mail addressed to your host in RFC 822 domain literal format,
"local_domains" must also include the appropriate `domains', consisting
of IP addresses enclosed in square brackets. The
"local_domains_include_host_literals" option can be set to add all IP
addresses automatically.

It is possible to specify no local domains by specifying no data for
this option, for example,

     local_domains =

If there are very many local domains, they can be stored in a file and
looked up whenever this string is searched. See the discussion of
domain lists in section "Domain lists" in chapter "The Exim
configuration file".


File: exim.info,  Node: local_domains_include_host,  Next: local_domains_include_host_literals,  Prev: local_domains,  Up: Main configuration

local_domains_include_host _option_
-----------------------------------

Type: boolean
Default: false

If this option is set, the value of "primary_hostname" is added to the
value of "local_domains", unless it is already present. This makes it
possible to use the same configuration file on a number of different
hosts.  The same effect can be obtained by including the conventional
item `@' (which matches the primary host name) in "local_domains".


File: exim.info,  Node: local_domains_include_host_literals,  Next: local_from_check,  Prev: local_domains_include_host,  Up: Main configuration

local_domains_include_host_literals _option_
--------------------------------------------

Type: boolean
Default: false

If this option is set and "local_interfaces" is unset, the IP addresses
of all the interfaces on the local host, with the exception of
127.0.0.1 (and ::1 on IPv6 systems), are added to the value of
"local_domains", in domain literal format, that is, as strings enclosed
in square brackets. If "local_interfaces" is set, only those addresses
it contains (again excluding 127.0.0.1 and ::1) are used.


File: exim.info,  Node: local_from_check,  Next: local_from_prefix,  Prev: local_domains_include_host_literals,  Up: Main configuration

local_from_check _option_
-------------------------

Type: boolean
Default: true

When a message is submitted locally (that is, not over a TCP/IP
connection) by a non-trusted user, Exim checks that the "From:" header
line matches the login of the calling user, and if not, it adds a
"Sender:" header.  If "local_from_check" is set false, this checking is
disabled, and no "Sender:" header is ever added. Nevertheless, the
envelope sender is still forced to be the login id at the qualify
domain.


File: exim.info,  Node: local_from_prefix,  Next: local_from_suffix,  Prev: local_from_check,  Up: Main configuration

local_from_prefix _option_
--------------------------

Type: string
Default: unset

When Exim checks the "From:" header line of locally submitted messages
for matching the login id (see "local_from_check" above), it can be
configured to ignore certain prefixes and suffixes in the local part of
the address. This is done by setting "local_from_prefix" and/or
"local_from_suffix" to appropriate lists, in the same form as the
prefix and suffix options of directors (see chapter "Additional generic
options for directors").  For example, if

     local_from_prefix = *-

is set, then a "From:" line containing

     From: anything-user@your.domain

will not cause a "Sender:" header to be added if "user@your.domain"
matches the actual sender address that is constructed from the login
name and qualify domain.


File: exim.info,  Node: local_from_suffix,  Next: local_interfaces,  Prev: local_from_prefix,  Up: Main configuration

local_from_suffix _option_
--------------------------

Type: string
Default: unset

See "local_from_prefix" above.


File: exim.info,  Node: local_interfaces,  Next: localhost_number,  Prev: local_from_suffix,  Up: Main configuration

local_interfaces _option_
-------------------------

Type: string list
Default: unset

The string must contain a list of IP addresses, in dotted-quad format
for IPv4 addresses, or in colon-separated format (with colons doubled)
for IPv6 addresses. These are used for two different purposes:

   * When a daemon is started to listen for incoming SMTP calls, it
     listens only on the interfaces identified here, that is, it calls
     "bind()" for these interfaces only. An error occurs if it is unable
     to bind a listening socket to any interface.

   * Only the IP addresses listed here are taken as the local host's
     addresses when routing mail and checking for mail loops.

If "local_interfaces" is unset, the daemon issues a generic "listen()"
that accepts incoming calls from any interface, and it also gets a
complete list of available interfaces and treats them all as local when
routing mail. On most systems the default action is what is wanted.
However, some systems set up large numbers of virtual interfaces in
order to provide many different virtual web servers. In these cases
"local_interfaces" can be used to restrict SMTP traffic to one or two
interfaces only. See also "hosts_treat_as_local".


File: exim.info,  Node: localhost_number,  Next: locally_caseless,  Prev: local_interfaces,  Up: Main configuration

localhost_number _option_
-------------------------

Type: string
Default: unset

Exim's message ids are normally unique only within the local host. If
uniqueness among a set of hosts is required, each host must set a
different value for the "localhost_number" option. The string is
expanded immediately after reading the configuration file (so that a
number can be computed from the host name, for example) and the result
of the expansion must be a number in the range 0-255. This is available
in subsequent string expansions via the variable $localhost_number.
The final two characters of the message id, instead of just being a
sequence count of the number of messages received by one process in one
second, are the base 62 encoding of

     <sequence count> * 256 + <local host number>

This reduces the possible range of the sequence count to 0-14. If the
count ever reaches 14 in a receiving process, a delay of one second is
imposed to allow the clock to tick, thereby allowing the count to be
reset to zero.


File: exim.info,  Node: locally_caseless,  Next: log_all_parents,  Prev: localhost_number,  Up: Main configuration

locally_caseless _option_
-------------------------

Type: boolean
Default: true

Domains in mail addresses are specified as being case-independent, but
this it not true of local parts. For most Unix systems, however, it is
desirable that local parts of local mail addresses be treated in a
case-independent manner, since most users expect that mail to "OBailey"
and "obailey", for example, will end up in the same mailbox. By
default, when it is processing an address whose domain is local, Exim
lower-cases the local part at the start of processing, on the
assumption that account names in the password file are in lower-case.

For installations that want to draw case distinctions, this option is
provided. When turned off, local local parts are handled verbatim
during delivery. If there are names containing upper case letters in the
password file, the most convenient way to provide for caseless mail
delivery is to set up a "smartuser" director as the first director, and
to make it do a lowercased lookup of the local part, in order to
translate it to the correctly cased version, using the "new_address"
option.


File: exim.info,  Node: log_all_parents,  Next: log_arguments,  Prev: locally_caseless,  Up: Main configuration

log_all_parents _option_
------------------------

Type: boolean
Default: false

This option applies to deliveries of local addresses, where the original
envelope address may be converted by (for example) an alias file into a
`child' address which might itself be an alias. Thus in general there
can be a chain of several addresses between the original one and the
address to which the actual delivery is made. By default Exim logs the
final address, followed by the original address in angle bracket.

Turning "log_all_parents" on causes all intermediate addresses between
the original envelope address and the final delivery address to be
included in delivery log lines in parentheses after the first address.
Without this, intermediate addresses are not included, except that if
the final delivery is to a pipe or file or autoreply, the immediately
preceding parent address is listed.


File: exim.info,  Node: log_arguments,  Next: log_file_path,  Prev: log_all_parents,  Up: Main configuration

log_arguments _option_
----------------------

Type: boolean
Default: false

Setting this option causes Exim to write the arguments with which it
was called to the main log. This is a debugging feature, added to make
it easy to find out with what arguments certain MUAs call
"/usr/lib/sendmail". The logging does not happen if Exim has given up
root privilege because it was called with the -C or -D options.  This
facility cannot log illegal arguments, because the arguments are checked
before the configuration file is read. The only way to log such cases
is to interpose a script such as "util/logargs.sh" between the caller
and Exim.


File: exim.info,  Node: log_file_path,  Next: log_incoming_port,  Prev: log_arguments,  Up: Main configuration

log_file_path _option_
----------------------

Type: string list
Default: set at compile time

This option sets the path which is used to determine the names of
Exim's log files, or indicates that logging is to be to "syslog", or
both. Chapter "Log files" contains further details. If this string is
fixed at your installation (contains no expansion variables) it is
recommended that you do not set this option in the configuration file,
but instead supply the path using LOG_FILE_PATH in `Local/Makefile' so
that it is available to Exim for logging errors detected early on - in
particular failure to read the configuration file.

If no specific path is set for the log files, they are written in a
sub-directory called "log" in Exim's spool directory.


File: exim.info,  Node: log_incoming_port,  Next: log_ip_options,  Prev: log_file_path,  Up: Main configuration

log_incoming_port _option_
--------------------------

Type: boolean
Default: false

If this option is set, the remote port number (separated by a dot) is
added to the IP address of incoming calls in all log entries, and in
"Received:" header lines. For example:

     127.0.0.1.48433
     ::1.48433

This is implemented by changing the value that is put in the
$sender_fullhost and $sender_rcvhost variables. Recording the remote
port number has become more important with the widening use of NAT (see
RFC 2505).


File: exim.info,  Node: log_ip_options,  Next: log_level,  Prev: log_incoming_port,  Up: Main configuration

log_ip_options _option_
-----------------------

Type: boolean
Default: true

See "kill_ip_options" above.


File: exim.info,  Node: log_level,  Next: log_queue_run_level,  Prev: log_ip_options,  Up: Main configuration

log_level _option_
------------------

Type: integer
Default: 5

This controls the amount of data written to the main log and to the
individual message logs (see section "Log level" in chapter "Log
files"). The higher the number, the more is written. At present a value
of 6 or higher causes all possible messages to appear.


File: exim.info,  Node: log_queue_run_level,  Next: log_received_recipients,  Prev: log_level,  Up: Main configuration

log_queue_run_level _option_
----------------------------

Type: integer
Default: 0

This option specifies the log level for the messages `start queue run'
and `end queue run'. Setting it higher than the value of "log_level"
causes them to be suppressed.


File: exim.info,  Node: log_received_recipients,  Next: log_received_sender,  Prev: log_queue_run_level,  Up: Main configuration

log_received_recipients _option_
--------------------------------

Type: boolean
Default: false

When this option is set, the recipients of a message are listed in the
main log as soon as the message is received. The list appears at the
end of the log line that is written when a message is received,
preceded by the word `for'. The addresses are listed after they have
been qualified, but before any rewriting has taken place.


File: exim.info,  Node: log_received_sender,  Next: log_refused_recipients,  Prev: log_received_recipients,  Up: Main configuration

log_received_sender _option_
----------------------------

Type: boolean
Default: false

If this option is set, the unrewritten original sender of a message is
added to the end of the log line that records the message's arrival,
after the word `from' (before the recipients if
"log_received_recipients" is also set).


File: exim.info,  Node: log_refused_recipients,  Next: log_rewrites,  Prev: log_received_sender,  Up: Main configuration

log_refused_recipients _option_
-------------------------------

Type: boolean
Default: false

If this option is set, an entry is written in the main and reject logs
for each recipient that is refused for policy reasons. Otherwise cases
where all recipients are to be refused just cause a single log entry
for the message.


File: exim.info,  Node: log_rewrites,  Next: log_sender_on_delivery,  Prev: log_refused_recipients,  Up: Main configuration

log_rewrites _option_
---------------------

Type: boolean
Default: false

This option causes all address rewriting to get logged, as an aid to
debugging rewriting rules.


File: exim.info,  Node: log_sender_on_delivery,  Next: log_smtp_confirmation,  Prev: log_rewrites,  Up: Main configuration

log_sender_on_delivery _option_
-------------------------------

Type: boolean
Default: false

Setting "log_sender_on_delivery" causes Exim to add an `F=<sender>' item
to delivery and bounce log lines (F is for `envelope from' - the same
letter as is used in rewriting rules). By default, the sender is not
shown on these lines.


File: exim.info,  Node: log_smtp_confirmation,  Next: log_smtp_connections,  Prev: log_sender_on_delivery,  Up: Main configuration

log_smtp_confirmation _option_
------------------------------

Type: boolean
Default: false

This option causes the response to the final `.' in the SMTP dialog for
outgoing messages to be added to delivery log lines in the form
`C="<text>"'.  A number of MTAs (including Exim from release 1.60)
return an identifying string in this response, so logging this
information allows messages to be tracked more easily. This global
option applies to all SMTP transports.


File: exim.info,  Node: log_smtp_connections,  Next: log_smtp_syntax_errors,  Prev: log_smtp_confirmation,  Up: Main configuration

log_smtp_connections _option_
-----------------------------

Type: boolean
Default: false

This option turns on more verbose logging of incoming SMTP connections,
at log level 4. This does not apply to batch SMTP, but it does apply to
SMTP connections from local processes that use the -bs option,
including incoming calls using "inetd". A log line is written whenever
a connection is established or closed. If a connection is dropped in
the middle of a message, a log line is always written, but otherwise
nothing is written at the start and end of connections unless
"log_smtp_connections" is set.


File: exim.info,  Node: log_smtp_syntax_errors,  Next: log_subject,  Prev: log_smtp_connections,  Up: Main configuration

log_smtp_syntax_errors _option_
-------------------------------

Type: boolean
Default: false

If this option is set, syntax errors in incoming SMTP commands are
logged at level 4.  An unrecognized command is treated as a syntax
error.  For an external connection, the host identity is given; for an
internal connection using -bs the sender identification (normally the
calling user) is given.


File: exim.info,  Node: log_subject,  Next: lookup_open_max,  Prev: log_smtp_syntax_errors,  Up: Main configuration

log_subject _option_
--------------------

Type: boolean
Default: false

This option causes a message's subject to be included in the arrival
log line, in the form `T="<subject text>"'. T stands for `topic' (S is
already used for `size').


File: exim.info,  Node: lookup_open_max,  Next: max_username_length,  Prev: log_subject,  Up: Main configuration

lookup_open_max _option_
------------------------

Type: integer
Default: 25

This option limits the number of simultaneously open lookup files. Exim
normally keeps files open during directing and routing, since often the
same file is required several times. This limit applies only to those
lookup types which use regular files, namely lsearch, dbm, and cdb. If
the limit is reached, Exim closes the least recently used file. Note
that if you are using the NDBM library, it actually opens two files for
each logical DBM database, though it still counts as one for the
purposes of "lookup_open_max". If you are getting `too many open files'
errors with NDBM, you need to reduce the value of "lookup_open_max".


File: exim.info,  Node: max_username_length,  Next: message_body_visible,  Prev: lookup_open_max,  Up: Main configuration

max_username_length _option_
----------------------------

Type: integer
Default: 0

Some operating systems are broken in that they truncate the argument to
"getpwnam()" to eight characters, instead of returning `no such user'.
If this option is set greater than zero, any attempt to call
"getpwnam()" with an argument that is longer behaves as if "getpwnam()"
failed.


File: exim.info,  Node: message_body_visible,  Next: message_filter,  Prev: max_username_length,  Up: Main configuration

message_body_visible _option_
-----------------------------

Type: integer
Default: 500

This option specifies how much of a message's body is to be included in
the "message_body" expansion variable.


File: exim.info,  Node: message_filter,  Next: message_filter_directory_transport,  Prev: message_body_visible,  Up: Main configuration

message_filter _option_
-----------------------

Type: string
Default: unset

This option specifies a filter file which is applied to all messages
before any routing or directing is done. This is called the `system
message filter'.  If the filter generates any deliveries to files or
pipes, or any new mail messages, the appropriate
"message_filter_..._transport" option(s) must be set, to define which
transports are to be used.  Details of this facility are given in
chapter "System-wide message filtering".


File: exim.info,  Node: message_filter_directory_transport,  Next: message_filter_directory2_transport,  Prev: message_filter,  Up: Main configuration

message_filter_directory_transport _option_
-------------------------------------------

Type: string
Default: unset

This sets the name of the transport driver that is to be used when the
"save" command in a system message filter specifies a path ending in
`/', implying delivery of each message into a separate file in some
directory.


File: exim.info,  Node: message_filter_directory2_transport,  Next: message_filter_file_transport,  Prev: message_filter_directory_transport,  Up: Main configuration

message_filter_directory2_transport _option_
--------------------------------------------

Type: string
Default: unset

This sets the name of the transport driver that is to be used when the
"save" command in a system message filter specifies a path ending in
`//'. The reason for having both "message_filter_directory" and
"message_filter_directory2" is to allow for the rare circumstance in
which both maildir and non-maildir format delivery is required.


File: exim.info,  Node: message_filter_file_transport,  Next: message_filter_group,  Prev: message_filter_directory2_transport,  Up: Main configuration

message_filter_file_transport _option_
--------------------------------------

Type: string
Default: unset

This sets the name of the transport driver that is to be used when the
"save" command in a system message filter specifies a path not ending
in `/'.


File: exim.info,  Node: message_filter_group,  Next: message_filter_pipe_transport,  Prev: message_filter_file_transport,  Up: Main configuration

message_filter_group _option_
-----------------------------

Type: string
Default: unset

This option sets the gid under which the system message filter is run.
The "seteuid()" or "setresuid()" function must be available in the
operating system for a temporary change to be possible. If the filter
generates any pipe, file, or reply addresses, the gid under which the
filter is run is used when delivering to them. Unless the string
consists entirely of digits, it is looked up using "getgrnam()", and
failure causes a configuration error. If the option is not set, and
either "message_filter_user" is unset or consists entirely of digits,
the gid is not changed when running the filter. Otherwise the group is
taken from the result of "getpwnam()".


File: exim.info,  Node: message_filter_pipe_transport,  Next: message_filter_reply_transport,  Prev: message_filter_group,  Up: Main configuration

message_filter_pipe_transport _option_
--------------------------------------

Type: string
Default: unset 7

This sets the name of the transport driver that is to be used when a
"pipe" command is used in a system message filter.


File: exim.info,  Node: message_filter_reply_transport,  Next: message_filter_user,  Prev: message_filter_pipe_transport,  Up: Main configuration

message_filter_reply_transport _option_
---------------------------------------

Type: string
Default: unset

This sets the name of the transport driver that is to be used when a
"mail" command is used in a system message filter.


File: exim.info,  Node: message_filter_user,  Next: message_id_header_text,  Prev: message_filter_reply_transport,  Up: Main configuration

message_filter_user _option_
----------------------------

Type: string
Default: unset

This option sets the uid under which the system message filter is run.
The "seteuid()" or "setresuid()" function must be available in the
operating system for a temporary change to be possible. If the filter
generates any pipe, file, or reply addresses, the uid under which the
filter is run is used when delivering to them. Unless it consists
entirely of digits, the string is looked up using "getpwnam()", and
failure causes a configuration error.  If the option is not set, the
uid is not changed from the Exim user (or root if there is no Exim
user) when running the system filter.


File: exim.info,  Node: message_id_header_text,  Next: message_size_limit,  Prev: message_filter_user,  Up: Main configuration

message_id_header_text _option_
-------------------------------

Type: string, expanded
Default: unset

If this variable is set, the string is expanded and used to augment the
text of the "Message-id:" header that Exim creates if an incoming
message does not have one. The text of this header is required by RFC
822 to take the form of an address. By default, Exim uses its internal
message id as the local part, and the primary host name as the domain.
If this option is set, it is expanded and provided the expansion does
not yield an empty string, is is inserted into the header immediately
before the @, separated from the internal message id by a dot. Any
characters that are illegal in an address are automatically converted
into hyphens. This means that constructions like "${tod_log}" can be
used, as the spaces and colons will become hyphens.


File: exim.info,  Node: message_size_limit,  Next: message_size_limit_count_recipients,  Prev: message_id_header_text,  Up: Main configuration

message_size_limit _option_
---------------------------

Type: integer
Default: 0

This option limits the maximum size of message that Exim will process.
Zero means no limit. It should be set somewhat larger than
"return_size_limit" if the latter is non-zero. Incoming SMTP messages
are failed with a 552 error if the limit is exceeded; locally-generated
messages either get a stderr message or a delivery failure message to
the sender, depending on the -oe setting, in the normal way. Rejection
of an oversized message is logged in both the main and the reject logs.
See also the generic transport option "message_size_limit", which
limits the size of message that an individual transport can process.


File: exim.info,  Node: message_size_limit_count_recipients,  Next: move_frozen_messages,  Prev: message_size_limit,  Up: Main configuration

message_size_limit_count_recipients _option_
--------------------------------------------

Type: boolean
Default: false

If this option is set, the value of "message_size_limit" is a maximum
for the size of a message times the number of envelope recipients it
has. For example, if "message_size_limit" is set to 10M, a message with
4 recipients can be no bigger than 2.5M, and a message with 100
recipients is limited to around 100K.


File: exim.info,  Node: move_frozen_messages,  Next: mysql_servers,  Prev: message_size_limit_count_recipients,  Up: Main configuration

move_frozen_messages _option_
-----------------------------

Type: boolean
Default: false

This option, which is available only if Exim has been built with the
setting

     SUPPORT_MOVE_FROZEN_MESSAGES=yes

in `Local/Makefile', causes frozen messages and their message logs to
be moved from the "input" and "msglog" directories on the spool to
"Finput" and "Fmsglog". There is currently no support in Exim or the
standard utilities for handling such moved messages, and they do not
show up in lists generated by -bp or by the Exim monitor.


File: exim.info,  Node: mysql_servers,  Next: never_users,  Prev: move_frozen_messages,  Up: Main configuration

mysql_servers _option_
----------------------

Type: string list
Default: unset

This option provides a list of MySQL servers and associated connection
data, to be used in conjunction with "mysql" lookups (see section "More
about MySQL and PostgreSQL" in chapter "File and database lookups"). The
option is available only if Exim has been built with MySQL support.


File: exim.info,  Node: never_users,  Next: nobody_group,  Prev: mysql_servers,  Up: Main configuration

never_users _option_
--------------------

Type: string list
Default: unset

Local mail deliveries are run in processes that are setuid to the
recipient. However, it is usually desirable to lock out root from this,
as a safety precaution. If a message is to be delivered locally as any
of the users on the "never_users" list, the process is run as `nobody'
instead (see "nobody_user" below). A common example is

     never_users = root:daemon:bin:exim

This option overrides the "pipe_as_creator" option of the "pipe"
transport driver. If Exim is unable to find a uid for `nobody', it
panics.


File: exim.info,  Node: nobody_group,  Next: nobody_user,  Prev: never_users,  Up: Main configuration

nobody_group _option_
---------------------

Type: string
Default: unset

This specifies the group to use when a process is to be run as
`nobody'. If it is unset, the value of the `nobody' user's default
group is used.


File: exim.info,  Node: nobody_user,  Next: percent_hack_domains,  Prev: nobody_group,  Up: Main configuration

nobody_user _option_
--------------------

Type: string
Default: unset

This specifies the user to use when a process is to be run as `nobody'.
If it is unset, Exim looks up the user `nobody' using "getpwnam()". If
this fails, Exim panics, writing a message to the panic log and exiting
immediately.


File: exim.info,  Node: percent_hack_domains,  Next: perl_at_start,  Prev: nobody_user,  Up: Main configuration

percent_hack_domains _option_
-----------------------------

Type: domain list
Default: unset

The `percent hack' is the convention whereby a local part containing a
percent sign is re-interpreted as a remote address, with the percent
replaced by @.  This is sometimes called `source routing', though that
term is also applied to RFC 822 addresses that begin with an @
character. If this option is set, Exim implements the percent facility
for those local domains listed, but no others.  The option can be set
to `*' to allow the percent hack for all local domains.

If options are set to control message relaying from incoming SMTP
envelopes, they are also applied to relaying that is requested via the
`percent hack'.  See section "Control of relaying" in chapter "Other
policy controls on incoming mail".


File: exim.info,  Node: perl_at_start,  Next: perl_startup,  Prev: percent_hack_domains,  Up: Main configuration

perl_at_start _option_
----------------------

Type: boolean
Default: false

This option is available only when Exim is built with an embedded Perl
interpreter. See chapter "Embedded Perl" for details of its use.


File: exim.info,  Node: perl_startup,  Next: pgsql_servers,  Prev: perl_at_start,  Up: Main configuration

perl_startup _option_
---------------------

Type: string
Default: unset

This option is available only when Exim is built with an embedded Perl
interpreter. See chapter "Embedded Perl" for details of its use.


File: exim.info,  Node: pgsql_servers,  Next: pid_file_path,  Prev: perl_startup,  Up: Main configuration

pgsql_servers _option_
----------------------

Type: string list
Default: unset

This option provides a list of PostgreSQL servers and associated
connection data, to be used in conjunction with "pgsql" lookups (see
section "More about MySQL and PostgreSQL" in chapter "File and database
lookups").  The option is available only if Exim has been built with
PostgreSQL support.


File: exim.info,  Node: pid_file_path,  Next: preserve_message_logs,  Prev: pgsql_servers,  Up: Main configuration

pid_file_path _option_
----------------------

Type: string
Default: set at compile time

This option sets the path which is used to determine the name of the
file to which the Exim daemon writes its process id. The string is
expanded, so it can contain, for example, references to the host name.
After expansion it must contain the string `%s' somewhere within it;
this will be replaced by the null string or a non-standard port number
to form the final file name. For example,

     pid_file_path = /var/log/${primary_hostname}/exim%s.pid

If no specific path is set for the file, it is written in Exim's spool
directory.


File: exim.info,  Node: preserve_message_logs,  Next: primary_hostname,  Prev: pid_file_path,  Up: Main configuration

preserve_message_logs _option_
------------------------------

Type: boolean
Default: false

If this option is set, message log files are not deleted when messages
are completed. Instead, they are moved to a sub-directory of the spool
directory called "msglog.OLD", where they remain available for
statistical or debugging purposes. This is a dangerous option to set on
systems with any appreciable volume of mail. Use with care!


File: exim.info,  Node: primary_hostname,  Next: print_topbitchars,  Prev: preserve_message_logs,  Up: Main configuration

primary_hostname _option_
-------------------------

Type: string
Default: see below

This specifies the name of the current host. This is used in the HELO
command for outgoing SMTP messages, and as the default for
"qualify_domain".  If it is not set, Exim calls "uname()" to find it.
If this fails, Exim panics and dies.  If the name returned by "uname()"
contains only one component, Exim passes it to "gethostbyname()" in
order to obtain the fully qualified version.


File: exim.info,  Node: print_topbitchars,  Next: prod_requires_admin,  Prev: primary_hostname,  Up: Main configuration

print_topbitchars _option_
--------------------------

Type: boolean
Default: false

By default, Exim considers only those characters whose codes lie in the
range 32-126 to be printing characters. In a number of circumstances
(for example, when writing log entries) non-printing characters are
converted into escape sequences, primarily to avoid messing up the
layout. If "print_topbitchars" is set, code values of 128 and above are
also considered to be printing characters.


File: exim.info,  Node: prod_requires_admin,  Next: prohibition_message,  Prev: print_topbitchars,  Up: Main configuration

prod_requires_admin _option_
----------------------------

Type: boolean
Default: true

The -M, -R, and -q command-line options require the caller to be an
admin user unless "prod_requires_admin" is set false. See also
"queue_list_requires_admin".


File: exim.info,  Node: prohibition_message,  Next: qualify_domain,  Prev: prod_requires_admin,  Up: Main configuration

prohibition_message _option_
----------------------------

Type: string, expanded
Default: unset

This option adds a site-specific message to the error response that is
sent when an SMTP command fails for policy reasons, for example if the
sending host is in a host reject list. Details of this facility are
given in chapter "Other policy controls on incoming mail".


File: exim.info,  Node: qualify_domain,  Next: qualify_recipient,  Prev: prohibition_message,  Up: Main configuration

qualify_domain _option_
-----------------------

Type: string
Default: see below

This specifies the domain name that is added to any sender addresses
that do not have a domain qualification. It also applies to recipient
addresses if "qualify_recipient" is not set. Such addresses are
accepted by default only for locally-generated messages - messages from
external sources must always contain fully qualified addresses, unless
the sending host matches one of the "receiver_unqualified" or
"sender_unqualified" options. If "qualify_domain" is not set, it
defaults to the "primary_hostname" value.


File: exim.info,  Node: qualify_recipient,  Next: queue_list_requires_admin,  Prev: qualify_domain,  Up: Main configuration

qualify_recipient _option_
--------------------------

Type: string
Default: see below

This specifies the domain name that is added to any recipient addresses
that do not have a domain qualification. Such addresses are accepted by
default only for locally-generated messages - messages from external
sources must always contain fully qualified addresses, unless the
sending host matches one of the "receiver_unqualified" or
"sender_unqualified" options (see below). If "qualify_recipient" is not
set, it defaults to the "qualify_domain" value.


File: exim.info,  Node: queue_list_requires_admin,  Next: queue_only,  Prev: qualify_recipient,  Up: Main configuration

queue_list_requires_admin _option_
----------------------------------

Type: boolean
Default: true

The -bp command-line option requires the caller to be an admin user
unless "queue_list_requires_admin" is set false. Otherwise, only
messages that the caller submitted are displayed. See also
"prod_requires_admin".


File: exim.info,  Node: queue_only,  Next: queue_only_file,  Prev: queue_list_requires_admin,  Up: Main configuration

queue_only _option_
-------------------

Type: boolean
Default: false

If "queue_only" is set (which is equivalent to the -odq command line
option), a delivery process is not automatically started whenever a
message has been received. Instead, the message waits on the queue for
the next queue run.  Even if "queue_only" is false, incoming SMTP
messages may not get delivered immediately if a lot of them arrive at
once - see the "queue_only_load" and "smtp_accept_queue" options.


File: exim.info,  Node: queue_only_file,  Next: queue_only_load,  Prev: queue_only,  Up: Main configuration

queue_only_file _option_
------------------------

Type: string
Default: unset

This option can be set to a colon-separated list of absolute path
names, each one optionally preceded by `remote' or `smtp'. When it is
receiving a message, Exim tests for the existence of each listed path
using a call to "stat()", and if this succeeds, the corresponding
queuing option is set. If there is no prefix to the path, "queue_only"
is set; `remote' corresponds to "queue_remote_domains" and `smtp' to
"queue_smtp_domains".  So, for example,

     queue_only_file = remote/some/file

causes Exim to behave as if "queue_remote_domains" were set to `*'
whenever "/some/file" exists.


File: exim.info,  Node: queue_only_load,  Next: queue_remote_domains,  Prev: queue_only_file,  Up: Main configuration

queue_only_load _option_
------------------------

Type: fixed-point
Default: unset

If the system load average is higher than this value, all incoming
messages are queued, and no automatic deliveries are started. If this
happens during local or remote SMTP input, all subsequent messages on
the same connection are queued. Deliveries will subsequently be
performed by queue running processes, unless the load is higher than
"deliver_load_max". There are some operating systems for which Exim
cannot determine the load average (see chapter 1); for these this
option has no effect. See also "smtp_accept_queue" and
"smtp_load_reserve".


File: exim.info,  Node: queue_remote_domains,  Next: queue_run_in_order,  Prev: queue_only_load,  Up: Main configuration

queue_remote_domains _option_
-----------------------------

Type: domain list
Default: unset

This option lists domains for which local delivery is not immediately
required.  It is checked against the domains supplied in the incoming
addresses, before any widening is done (because that is part of
routing). The -odqr option is equivalent to setting
"queue_remote_domains" to `*'. A delivery process is started whenever a
message is received, but only local addresses are handled, and only
local deliveries take place. All remote deliveries wait until the next
queue run. See also "queue_smtp_domains", which is subtly different.


File: exim.info,  Node: queue_run_in_order,  Next: queue_run_max,  Prev: queue_remote_domains,  Up: Main configuration

queue_run_in_order _option_
---------------------------

Type: boolean
Default: false

If this option is set, queue runs happen in order of message arrival
instead of in an arbitrary order.  In order for this to happen, a
complete list of the entire queue must be set up before the deliveries
start. When the queue is all in a single directory (the default), this
happens anyway, but if "split_spool_directory" is set it does not - for
delivery in random order, the sub-directories are processed one at a
time (in random order), to avoid setting up one huge list. Thus, setting
"queue_run_in_order" with "split_spool_directory" may degrade
performance when the queue is large. In most situations,
"queue_run_in_order" should not be set.


File: exim.info,  Node: queue_run_max,  Next: queue_smtp_domains,  Prev: queue_run_in_order,  Up: Main configuration

queue_run_max _option_
----------------------

Type: integer
Default: 5

This controls the maximum number of queue-running processes that an
Exim daemon will run simultaneously. This does not mean that it starts
them all at once, but rather that if the maximum number are still
running when the time comes to start another one, it refrains from
starting it. This can happen with very large queues and/or very
sluggish deliveries. This option does not, however, interlock with
other processes, so additional queue-runners can be started by other
means, or by killing and restarting the daemon.


File: exim.info,  Node: queue_smtp_domains,  Next: rbl_domains,  Prev: queue_run_max,  Up: Main configuration

queue_smtp_domains _option_
---------------------------

Type: domain list
Default: unset

When this option is set, a delivery process is started whenever a
message is received, directing and routing is performed, and local
deliveries take place.  However, if any SMTP deliveries are required
for domains that match "queue_smtp_domains", they are not immediately
delivered, but instead the message waits on the queue for the next
queue run. Since routing of the message has taken place, Exim knows to
which remote hosts it must be delivered, and so when the queue run
happens, multiple messages for the same host are delivered over a
single SMTP connection. This option is checked against the domains
supplied in the incoming addresses, before any widening is done
(because that is part of routing). The -odqs command line option causes
all SMTP deliveries to be queued in this way, and is equivalent to
setting "queue_smtp_domains" to `*'. See also "queue_remote_domains",
which is subtly different.


File: exim.info,  Node: rbl_domains,  Next: rbl_hosts,  Prev: queue_smtp_domains,  Up: Main configuration

rbl_domains _option_
--------------------

Type: string list
Default: unset

This option is part of the support for Realtime Blackhole Lists (RBL).
It can be set to a colon-separated list of DNS domains in which to look
up the IP address of a calling host. A full description of how this is
used is given in section "Host checking using RBL" in chapter "Other
policy controls on incoming mail".


File: exim.info,  Node: rbl_hosts,  Next: rbl_log_headers,  Prev: rbl_domains,  Up: Main configuration

rbl_hosts _option_
------------------

Type: host list
Default: *

This option specifies the set of hosts for which RBL checking is to be
performed when "rbl_domains" is set. The default matches all hosts. The
normal usage of this option is to specify exceptions to RBL checking by
means of negated items in the host list.


File: exim.info,  Node: rbl_log_headers,  Next: rbl_log_rcpt_count,  Prev: rbl_hosts,  Up: Main configuration

rbl_log_headers _option_
------------------------

Type: boolean
Default: false

When this option is set, the headers of each message received from a
host that matches an RBL domain are written to the reject log. This can
occur only if the recipients of the message are not rejected, that is,
if the RBL check is configured to warn only.


File: exim.info,  Node: rbl_log_rcpt_count,  Next: rbl_reject_recipients,  Prev: rbl_log_headers,  Up: Main configuration

rbl_log_rcpt_count _option_
---------------------------

Type: boolean
Default: false

When this option is set and "rbl_reject_recipients" is false, the
number of RCPT commands for each message received from a host that is
in the RBL is written to the reject log. This may be greater than the
number of valid recipients in the message.


File: exim.info,  Node: rbl_reject_recipients,  Next: rbl_warn_header,  Prev: rbl_log_rcpt_count,  Up: Main configuration

rbl_reject_recipients _option_
------------------------------

Type: boolean
Default: true

This option controls the action taken when a remote host is found in an
RBL domain that has neither `/warn' nor `/reject' following it. The
default value specifies rejection.


File: exim.info,  Node: rbl_warn_header,  Next: received_header_text,  Prev: rbl_reject_recipients,  Up: Main configuration

rbl_warn_header _option_
------------------------

Type: boolean
Default: true

When this option is set and a message from an RBL-matching host is not
rejected, an "X-RBL-Warning:" header is added. The header contains the
contents of the DNS TXT record, if one was found. Scanning of further
RBL domains continues, which means that more than one "X-RBL-Warning:"
header may be added to a message.


File: exim.info,  Node: received_header_text,  Next: received_headers_max,  Prev: rbl_warn_header,  Up: Main configuration

received_header_text _option_
-----------------------------

Type: string, expanded
Default: see below

This string defines the contents of the "Received:" message header that
is added to each message, except for the timestamp, which is
automatically added on at the end, preceded by a semicolon. The string
is expanded each time it is used, and the default is:

     received_header_text = "Received: \
         ${if def:sender_rcvhost {from ${sender_rcvhost}\n\t}\
         {${if def:sender_ident {from ${sender_ident} }}\
         ${if def:sender_helo_name {(helo=${sender_helo_name})\n\t}}}}\
         by ${primary_hostname} \
         ${if def:received_protocol {with ${received_protocol}}} \
         ${if def:tls_cipher {($tls_cipher)\n\t}}\
         (Exim ${version_number} #${compile_number})\n\t\
         id ${message_id}\
         ${if def:received_for {\n\tfor $received_for}}"

Note the use of quotes, to allow the sequences `\n' and `\t' to be used
for newlines and tabs, respectively. The reference to the TLS cipher is
omitted when Exim is built without TLS support.  The use of conditional
expansions ensures that this works for both locally generated messages
and messages received from remote hosts, giving header lines such as
the following:

     Received: from scrooge.carol.book ([240.1.12.25] ident=root)
             by marley.carol.book with smtp (Exim 3.30 #1)
             id E0tS3Ga-0005C5-00
             for cratchit@dickens.book; Mon, 25 Dec 2000 14:43:44 +0000
     Received: by scrooge.carol.book with local (Exim 3.30 #1)
             id E0tS3GW-0005C2-00; Mon, 25 Dec 2000 14:43:41 +0000

Note the automatic addition of the date and time in the required format.


File: exim.info,  Node: received_headers_max,  Next: receiver_try_verify,  Prev: received_header_text,  Up: Main configuration

received_headers_max _option_
-----------------------------

Type: integer
Default: 30

When a message is to be delivered, the number of "Received:" headers is
counted, and if it is greater than this parameter, a mail loop is
assumed to have occurred, the delivery is abandoned, and an error
message is generated.  This applies to both local and remote
deliveries. Earlier versions of Exim did this test only for remote
deliveries, but because local deliveries (as Exim sees them) may in
fact still cause a message to be transported to a remote host, it was
changed.


File: exim.info,  Node: receiver_try_verify,  Next: receiver_unqualified_hosts,  Prev: received_headers_max,  Up: Main configuration

receiver_try_verify _option_
----------------------------

Type: boolean
Default: false

See "receiver_verify".


File: exim.info,  Node: receiver_unqualified_hosts,  Next: receiver_verify,  Prev: receiver_try_verify,  Up: Main configuration

receiver_unqualified_hosts _option_
-----------------------------------

Type: host list
Default: unset

This option lists those hosts from which Exim is prepared to accept
unqualified receiver addresses in message envelopes.  The addresses are
made fully qualified by the addition of the "qualify_recipient" value.
Typically the hosts are local ones, but if you want to imitate the
behaviour of mailers that accept unqualified addresses from anywhere,
specify

     receiver_unqualified_hosts = *

This option also affects message header lines. Exim does not reject
unqualified receiver addresses in headers, but qualifies them only if
the message came from a host that matches "receiver_unqualified_hosts".


File: exim.info,  Node: receiver_verify,  Next: receiver_verify_addresses,  Prev: receiver_unqualified_hosts,  Up: Main configuration

receiver_verify _option_
------------------------

Type: boolean
Default: false

When this option is set, the addresses of recipients received from a
remote host are verified as they are received, provided the sending
host matches "receiver_verify_hosts", the incoming address matches
"receiver_verify_addresses", and the sender address matches
"receiver_verify_senders", if either of the last two are set.

If an address is invalid, an incoming SMTP call gets an error response
to the RCPT command. If an address cannot immediately be verified, a
temporary error code is given. The "receiver_try_verify" option is less
severe: it operates in the same way, except that an address is accepted
if it cannot immediately be verified. Verification failures are logged.


File: exim.info,  Node: receiver_verify_addresses,  Next: receiver_verify_hosts,  Prev: receiver_verify,  Up: Main configuration

receiver_verify_addresses _option_
----------------------------------

Type: address list
Default: unset

If set, this option restricts receiver verification to those addresses
it matches. The option is inspected only if "receiver_verify" or
"receiver_try_verify" is set.


File: exim.info,  Node: receiver_verify_hosts,  Next: receiver_verify_senders,  Prev: receiver_verify_addresses,  Up: Main configuration

receiver_verify_hosts _option_
------------------------------

Type: host list
Default: *

See "receiver_verify" above.


File: exim.info,  Node: receiver_verify_senders,  Next: recipients_max,  Prev: receiver_verify_hosts,  Up: Main configuration

receiver_verify_senders _option_
--------------------------------

Type: address list
Default: unset

This option, if set, allows receiver verification to be conditional
upon the sender. It is inspected only if "receiver_verify" or
"receiver_try_verify" is set.

If the null sender is required in the list of addresses, it must not be
the last item, as a null last item in a list is ignored. It is best
placed at the start of the list. For example, to restrict receiver
verification to messages with null senders and senders in the ".com"
and ".org" domains, you could have

     receiver_verify
     receiver_verify_senders = :*.com:*.org

If the null sender is the only entry required, the list should consist
of a single colon.


File: exim.info,  Node: recipients_max,  Next: recipients_max_reject,  Prev: receiver_verify_senders,  Up: Main configuration

recipients_max _option_
-----------------------

Type: integer
Default: 0

If this is set greater than zero, it specifies the maximum number of
recipients for any message. This applies to the original list of
recipients supplied with the message. SMTP messages get a 452 response
for all recipients over the limit; earlier recipients are delivered as
normal. Non-SMTP messages with too many recipients are failed, and no
deliveries are done.  Note that the RFCs specify that an SMTP server
should accept at least 100 RCPT commands in a single message.


File: exim.info,  Node: recipients_max_reject,  Next: recipients_reject_except,  Prev: recipients_max,  Up: Main configuration

recipients_max_reject _option_
------------------------------

Type: boolean
Default: false

If this option is set true, Exim rejects SMTP messages containing too
many recipients by giving 552 errors to the surplus RCPT commands, and
a 554 error to the eventual DATA command. Otherwise (the default) it
gives a 452 error to the surplus RCPT commands and accepts the message
on behalf of the initial set of recipients. The remote server should
then re-send the message for the remaining recipients at a later time.


File: exim.info,  Node: recipients_reject_except,  Next: recipients_reject_except_senders,  Prev: recipients_max_reject,  Up: Main configuration

recipients_reject_except _option_
---------------------------------

Type: address list
Default: unset

This option lists recipient addresses which are exceptions to any
policy for recipient rejection, that is, as a result of
"sender_reject_recipients", etc.  This option is entirely independent
of any checks for unwanted message relaying. However, it does interact
with the RBL options.


File: exim.info,  Node: recipients_reject_except_senders,  Next: refuse_ip_options,  Prev: recipients_reject_except,  Up: Main configuration

recipients_reject_except_senders _option_
-----------------------------------------

Type: address list
Default: unset

This option lists sender addresses for which recipients are excepted
from any policy rejections. That is, if a message comes from any of
these senders, all its recipients are excepted from policy rejections.


File: exim.info,  Node: refuse_ip_options,  Next: relay_domains,  Prev: recipients_reject_except_senders,  Up: Main configuration

refuse_ip_options _option_
--------------------------

Type: boolean
Default: true

See "kill_ip_options" above.


File: exim.info,  Node: relay_domains,  Next: relay_domains_include_local_mx,  Prev: refuse_ip_options,  Up: Main configuration

relay_domains _option_
----------------------

Type: domain list
Default: unset

This option lists domains for which the local host is prepared to relay.
See section "Control of relaying" in chapter "Other policy controls on
incoming mail" for details of relay control.


File: exim.info,  Node: relay_domains_include_local_mx,  Next: relay_match_host_or_sender,  Prev: relay_domains,  Up: Main configuration

relay_domains_include_local_mx _option_
---------------------------------------

Type: boolean
Default: false

This option permits any host to relay to any domain that has an MX
record pointing at the local host. It causes any domain with an MX
record pointing at the local host to be treated as if it were in
"relay_domains". See section "Control of relaying" in chapter "Other
policy controls on incoming mail" for details of relay control.


File: exim.info,  Node: relay_match_host_or_sender,  Next: remote_max_parallel,  Prev: relay_domains_include_local_mx,  Up: Main configuration

relay_match_host_or_sender _option_
-----------------------------------

Type: boolean
Default: false

By default, if relaying controls are specified on both the remote host
and the sender address, a message is accepted only if both conditions
are met. If "relay_match_host_or_sender" is set, either condition is
good enough.  It does not make sense to set this option without setting
"sender_address_relay", since if that option is unset it matches all
senders.  Exim therefore diagnoses a configuration error in this case.
See section "Control of relaying" in chapter "Other policy controls on
incoming mail" for details of relay control.


File: exim.info,  Node: remote_max_parallel,  Next: remote_sort,  Prev: relay_match_host_or_sender,  Up: Main configuration

remote_max_parallel _option_
----------------------------

Type: integer
Default: 1

This option controls parallel delivery to remote sites. If the value is
less than 2, parallel delivery is disabled, and Exim does all the
remote deliveries for a message one by one, from a single delivery
process. Otherwise, if a message has to be delivered to more than one
remote host, or if several copies have to be sent to the same remote
host, then up to "remote_max_parallel" deliveries are done
simultaneously, each in a separate process. If more than
"remote_max_parallel" deliveries are required, the maximum number of
processes are started, and as each one finishes, another is begun. The
order of starting processes is the same as if sequential delivery were
being done, and can be controlled by the "remote_sort" option. If
parallel delivery takes place while running with debugging turned on,
the debugging output from each delivery process is tagged with its
process id.

The overhead in doing this is a fork to set up a separate process for
each delivery, and the associated management of the subprocess
(including getting back the result of the delivery attempt). As well as
the process overhead, there may be a small additional penalty paid for
parallel delivery. If a host is found to be down, this fact cannot be
communicated to any deliveries that are running in parallel, though it
will be passed on to any that start afterwards. This is no worse than
if there were two separate messages being delivered simultaneously.

The option controls only the maximum number of parallel deliveries from
one Exim process. Since Exim has no central queue manager, there is no
way of controlling the total number of simultaneous deliveries if the
configuration allows a delivery attempt as soon as a message is
received.  If you want to control the total number of deliveries on the
system, you need to set the "queue_only" option, which ensures that all
incoming messages are simply added to the queue. Then set up an Exim
daemon to start queue runner processes at appropriate intervals
(probably fairly often, for example, every minute), and limit the total
number of queue runners by setting the "queue_run_max" parameter.
Because each queue runner delivers only one message at a time, the
maximum number of deliveries that can then take place at once is
"queue_run_max" multiplied by "remote_max_parallel".

If it is purely remote deliveries you want to control, use "queue_smtp"
instead of "queue_only". This has the added benefit of doing the SMTP
routing before queuing, so that several messages for the same host will
eventually get delivered down the same connection.


File: exim.info,  Node: remote_sort,  Next: retry_data_expire,  Prev: remote_max_parallel,  Up: Main configuration

remote_sort _option_
--------------------

Type: domain list
Default: unset

When there are a number of remote deliveries for a message, they are
sorted by domain into the order given by this list. For example,

     remote_sort = *.cam.ac.uk:*.uk

would attempt to deliver to all addresses in the "cam.ac.uk" domain
first, then to those in the "uk" domain, then to any others.


File: exim.info,  Node: retry_data_expire,  Next: retry_interval_max,  Prev: remote_sort,  Up: Main configuration

retry_data_expire _option_
--------------------------

Type: time
Default: 7d

This option sets a `use before' time on retry information in Exim's
hints database. Any older retry data is ignored. This means that, for
example, once a host has not been tried for 7 days, Exim behaves as if
it has no knowledge of past failures.


File: exim.info,  Node: retry_interval_max,  Next: return_path_remove,  Prev: retry_data_expire,  Up: Main configuration

retry_interval_max _option_
---------------------------

Type: time
Default: 24h

Chapter "Retry configuration" describes Exim's mechanisms for
controlling the intervals between delivery attempts for messages that
cannot be delivered straight away.  This option sets an overall limit
to the length of time between retries.


File: exim.info,  Node: return_path_remove,  Next: return_size_limit,  Prev: retry_interval_max,  Up: Main configuration

return_path_remove _option_
---------------------------

Type: boolean
Default: true

RFC 822 states that the "Return-path:" header is `added by the final
transport system that delivers the message to its recipient' (section
4.3.1), which implies that this header should not be present in an
incoming message, where the return path is carried in the envelope.  If
this option is true, any existing "Return-path:" headers are removed
from messages as they are read. Exim's transports have options for
adding "Return-path:" headers at the time of delivery. They are
normally used only for final local deliveries.


File: exim.info,  Node: return_size_limit,  Next: rfc1413_hosts,  Prev: return_path_remove,  Up: Main configuration

return_size_limit _option_
--------------------------

Type: integer
Default: 100K

This option sets a limit in bytes on the size of messages that are
returned to senders. If it is set to zero there is no limit. If the
body of any message that is to be included in an error report is
greater than the limit, it is truncated, and a comment pointing this
out is added at the top. The actual cutoff may be greater than the
value given, owing to the use of buffering for transferring the message
in chunks. The idea is just to save bandwidth on those undeliverable
15-megabyte messages. If either the global or generic transport
"message_size_limit" is set, the value of "return_size_limit" should be
somewhat smaller.


File: exim.info,  Node: rfc1413_hosts,  Next: rfc1413_query_timeout,  Prev: return_size_limit,  Up: Main configuration

rfc1413_hosts _option_
----------------------

Type: host list
Default: *

RFC 1413 identification calls are made to any host which matches an
item in the list. The items in the host list should not themselves
contain ident data.


File: exim.info,  Node: rfc1413_query_timeout,  Next: security,  Prev: rfc1413_hosts,  Up: Main configuration

rfc1413_query_timeout _option_
------------------------------

Type: time
Default: 30s

This sets the timeout on RFC 1413 identification calls. If it is set to
zero, no RFC 1413 calls are ever made.


File: exim.info,  Node: security,  Next: sender_address_relay,  Prev: rfc1413_query_timeout,  Up: Main configuration

security _option_
-----------------

Type: string
Default: see below

When "exim_user" is set non-zero in the run time configuration or an
Exim uid is compiled into the binary, Exim gives up root privilege for
some of the time.  As there are trade-offs between increased security
and efficiency, this option is provided to control exactly how this is
done. The option can be set to one of the strings `seteuid', `setuid',
`setuid+seteuid' or `unprivileged', provided that a uid for Exim is
defined. Otherwise it must be left unset. A full description of what
these values mean is given in chapter "Security considerations".  The
default for this option is unset if no special Exim uid is defined,
otherwise it is either `setuid+seteuid' or `setuid', depending on
whether the "seteuid()" function is configured as being available or
not.


File: exim.info,  Node: sender_address_relay,  Next: sender_address_relay_hosts,  Prev: security,  Up: Main configuration

sender_address_relay _option_
-----------------------------

Type: address list
Default: unset

This option specifies a set of address patterns, one of which the
sender of a message must match in order for the message to be accepted
for outgoing relaying, that is, relaying from specified hosts to
arbitrary domains.  The check does not operate for incoming relaying,
that is, for addresses that match "relay_domains".

If this option is not set, all sender addresses are permitted. By
default, the check operates in addition to any relaying checks on the
sending host (see "host_accept_relay" above). However, if
"relay_match_host_or_sender" is set, either a host match or a sender
match is sufficient to allow the relaying to proceed. For this reason,
"sender_address_relay" is required to be set if
"relay_match_host_or_sender" is set.

Warning: Sender addresses can be trivially forged. For this reason,
setting "relay_match_host_or_sender" is strongly discouraged.

The rewrite flag X (see section "The additional relay checking flag" in
chapter "Address rewriting") provides a special-purpose facility we
have a use for in Cambridge. It adds additional checking to
"sender_address_relay". Whenever a sender address passes the check, if
there are any rewriting rules with the X flag set, the address is
rewritten using those rules, and if this makes any change to the
address, the new address must verify successfully for the relaying to be
permitted.


File: exim.info,  Node: sender_address_relay_hosts,  Next: sender_reject,  Prev: sender_address_relay,  Up: Main configuration

sender_address_relay_hosts _option_
-----------------------------------

Type: host list
Default: *

The hosts to which "sender_address_relay" is applied can be controlled
by this option. This is useful in a cluster where one host is delegated
as a fallback to hold all the delayed deliveries. It needs to be able
to relay from the other hosts without sender checking (for example, for
messages forwarded by local users) but might want to check senders in
messages relayed from other hosts.


File: exim.info,  Node: sender_reject,  Next: sender_reject_recipients,  Prev: sender_address_relay_hosts,  Up: Main configuration

sender_reject _option_
----------------------

Type: address list
Default: unset

This option can be set in order to reject mail from certain senders.
The check is done on the sender's address as given in the MAIL command
in SMTP, but not for local senders where the logged-in user's address
is going to override anyway.

The check is not done for batch SMTP input. If the check fails, a 550
return code is given to MAIL. This doesn't always stop remote mailers
from trying again. See "sender_reject_recipients" for an alternative.
Typical examples of the use of this option might be:

     sender_reject = spamuser@some.domain:spam.domain
     sender_reject = partial-dbm;/etc/mail/blocked/senders

Note that this check operates on sender address domains independently
of the sending host; "host_reject" can be used to block all mail from
particular hosts, while "host_accept_relay", and "sender_address_relay"
can be used to prevent unwanted relaying.


File: exim.info,  Node: sender_reject_recipients,  Next: sender_try_verify,  Prev: sender_reject,  Up: Main configuration

sender_reject_recipients _option_
---------------------------------

Type: address list
Default: unset

This operates in exactly the same way as "sender_reject" except that the
rejection is given in the form of a 550 error code to every RCPT command
instead of rejecting MAIL. This seems to be the only way of saying `no'
to some mailers. Note that this is not an option for rejecting specific
recipients. The way to do that is to set "receiver_verify" and arrange
for those recipients to fail verification.


File: exim.info,  Node: sender_try_verify,  Next: sender_unqualified_hosts,  Prev: sender_reject_recipients,  Up: Main configuration

sender_try_verify _option_
--------------------------

Type: boolean
Default: false

See "sender_verify".


File: exim.info,  Node: sender_unqualified_hosts,  Next: sender_verify,  Prev: sender_try_verify,  Up: Main configuration

sender_unqualified_hosts _option_
---------------------------------

Type: host list
Default: unset

This option lists those hosts from which Exim is prepared to accept
unqualified sender addresses. The addresses are made fully qualified by
the addition of "qualify_domain". Typically the hosts are local ones,
but if you want to imitate the behaviour of mailers that accept
unqualified addresses from anywhere, specify

     sender_unqualified_hosts = *

This option also affects message header lines. Exim does not reject
unqualified addresses in headers containing sender addresses, but
qualifies them only if the message came from a host that matches
"sender_unqualified_hosts".


File: exim.info,  Node: sender_verify,  Next: sender_verify_batch,  Prev: sender_unqualified_hosts,  Up: Main configuration

sender_verify _option_
----------------------

Type: boolean
Default: false

If this option is true, envelope sender addresses on incoming SMTP
messages are checked to ensure that they are valid. Messages with
invalid envelope senders are rejected with a permanent error code if
"sender_verify_reject" is set (the default). Otherwise a warning is
logged. See section "Sender verification" in chapter "Verification of
incoming mail" for details of the rejection, which can happen at three
different points in the SMTP dialogue. If a sender cannot immediately be
verified, a temporary error code is returned after reading the data (so
the headers can be logged). The "sender_try_verify" option is less
severe: it operates in exactly the same way as "sender_verify" except
that if an address cannot immediately be verified, it is accepted
instead of being temporarily rejected.


File: exim.info,  Node: sender_verify_batch,  Next: sender_verify_callback_domains,  Prev: sender_verify,  Up: Main configuration

sender_verify_batch _option_
----------------------------

Type: boolean
Default: false

If this option is unset, the "sender_verify" options are not applied to
batched SMTP input.


File: exim.info,  Node: sender_verify_callback_domains,  Next: sender_verify_callback_timeout,  Prev: sender_verify_batch,  Up: Main configuration

sender_verify_callback_domains _option_
---------------------------------------

Type: domain list
Default: unset

When a sender address is being verified, an SMTP `callback' to one of
the hosts that handle mail for its domain occurs if the sender's domain
matches "sender_verify_callback_domains" and the sending host matches
"sender_verify_hosts_callback" (in addition to "sender_verify_hosts").
See section "Sender verification with callback" in chapter
"Verification of incoming mail" for details.


File: exim.info,  Node: sender_verify_callback_timeout,  Next: sender_verify_fixup,  Prev: sender_verify_callback_domains,  Up: Main configuration

sender_verify_callback_timeout _option_
---------------------------------------

Type: time
Default: 30s

This option specifies a timeout for sender verification callbacks.


File: exim.info,  Node: sender_verify_fixup,  Next: sender_verify_hosts,  Prev: sender_verify_callback_timeout,  Up: Main configuration

sender_verify_fixup _option_
----------------------------

Type: boolean
Default: false

Experience shows that many messages are sent out onto the Internet with
invalid sender addresses in the envelopes (that is, in the MAIL command
of the SMTP dialogue), but with valid addresses in the "Sender:",
"From:", or "Reply-To:" header fields. If "sender_verify" and
"sender_verify_reject" are true and this option is also true, an
invalid envelope sender or one that cannot immediately be verified is
replaced by a valid value from the headers.  If "sender_verify_reject"
is false, the envelope sender is not changed, but Exim writes a log
entry giving the correction it would have made. See chapter
"Verification of incoming mail" for details.


File: exim.info,  Node: sender_verify_hosts,  Next: sender_verify_hosts_callback,  Prev: sender_verify_fixup,  Up: Main configuration

sender_verify_hosts _option_
----------------------------

Type: host list
Default: *

If "sender_verify" or "sender_try_verify" is true, this option
specifies a list of hosts and RFC 1413 identifications to which sender
verification applies. The check caused by "headers_sender_verify" also
happens only for matching hosts. See chapter "Verification of incoming
mail" for further details.


File: exim.info,  Node: sender_verify_hosts_callback,  Next: sender_verify_max_retry_rate,  Prev: sender_verify_hosts,  Up: Main configuration

sender_verify_hosts_callback _option_
-------------------------------------

Type: host list
Default: unset

See "sender_verify_callback_domains" above.


File: exim.info,  Node: sender_verify_max_retry_rate,  Next: sender_verify_reject,  Prev: sender_verify_hosts_callback,  Up: Main configuration

sender_verify_max_retry_rate _option_
-------------------------------------

Type: integer
Default: 12

If this option is greater than zero, and the rate of temporary
rejection of a specific incoming sender address from a specific host,
in units of rejections per hour, exceeds it, the temporary error is
converted into a permanent verification error. Temporary rejections
most commonly occur when a sender address cannot be verified because a
DNS lookup fails to complete.

The intent of this option is to stop hosts hammering too frequently with
temporarily failing sender addresses. The default value of 12 means
that a sender address that has a temporary verification error more than
once every 5 minutes will eventually get permanently rejected. Once
permanent rejection has been triggered, subsequent temporary failures
all cause permanent errors, until there has been an interval of at
least 24 hours since the last failure. After 24 hours, the hint expires.


File: exim.info,  Node: sender_verify_reject,  Next: smtp_accept_keepalive,  Prev: sender_verify_max_retry_rate,  Up: Main configuration

sender_verify_reject _option_
-----------------------------

Type: boolean
Default: true

When this is set, a message is rejected if sender verification fails.
If it is not set, a warning message is written to the main and reject
logs, and the message is accepted (unless some other error occurs).


File: exim.info,  Node: smtp_accept_keepalive,  Next: smtp_accept_max,  Prev: sender_verify_reject,  Up: Main configuration

smtp_accept_keepalive _option_
------------------------------

Type: boolean
Default: true

This option controls the setting of the SO_KEEPALIVE option on incoming
TCP/IP socket connections. This causes the kernel periodically to send
some OOB (out-of-band) data on idle connections. The reason for doing
this is that it has the beneficial effect of freeing up certain types
of connection that can get stuck when the remote host is disconnected
without tidying up the TCP/IP call properly.


File: exim.info,  Node: smtp_accept_max,  Next: smtp_accept_max_per_host,  Prev: smtp_accept_keepalive,  Up: Main configuration

smtp_accept_max _option_
------------------------

Type: integer
Default: 20

This specifies the maximum number of simultaneous incoming SMTP calls
that Exim will accept. It applies only to the listening daemon; there
is no control (in Exim) when incoming SMTP is being handled by "inetd".
If the value is set to zero, no limit is applied.  However, it is
required to be non-zero if "smtp_accept_max_per_host" or
"smtp_accept_queue" is set.


File: exim.info,  Node: smtp_accept_max_per_host,  Next: smtp_accept_queue,  Prev: smtp_accept_max,  Up: Main configuration

smtp_accept_max_per_host _option_
---------------------------------

Type: integer
Default: 0

This option restricts the number of simultaneous IP connections from a
single host (strictly, from a single IP address) to the Exim daemon.
Once the limit is reached, additional connection attempts are rejected
with error code 421.  The default value of zero imposes no limit. If
this option is not zero, it is required that "smtp_accept_max" also be
non-zero.


File: exim.info,  Node: smtp_accept_queue,  Next: smtp_accept_queue_per_connection,  Prev: smtp_accept_max_per_host,  Up: Main configuration

smtp_accept_queue _option_
--------------------------

Type: integer
Default: 0

If the number of simultaneous incoming SMTP calls handled via the
listening daemon exceeds this value, messages received are simply
placed on the queue, and no delivery processes are started
automatically. A value of zero implies no limit, and clearly any
non-zero value is useful only if it is less than the "smtp_accept_max"
value (unless that is zero). See also "queue_only", "queue_only_load",
"queue_smtp_domains", and the various -od command line options.


File: exim.info,  Node: smtp_accept_queue_per_connection,  Next: smtp_accept_reserve,  Prev: smtp_accept_queue,  Up: Main configuration

smtp_accept_queue_per_connection _option_
-----------------------------------------

Type: integer
Default: 10

This option limits the number of delivery processes that Exim starts
automatically when receiving messages via SMTP, whether via the daemon
or by the use of -bs or -bS. If the value of the option is greater than
zero, and the number of messages received in a single SMTP session
exceeds this number, subsequent messages are placed on the spool, but
no delivery process is started. This helps to limit the number of Exim
processes when a server restarts after downtime and there is a lot of
mail waiting for it on other systems. On large systems the default
should probably be increased, while on dial-in client systems it should
probably be set to zero (that is, disabled).


File: exim.info,  Node: smtp_accept_reserve,  Next: smtp_banner,  Prev: smtp_accept_queue_per_connection,  Up: Main configuration

smtp_accept_reserve _option_
----------------------------

Type: integer
Default: 0

When "smtp_accept_max" is set greater than zero, this option specifies a
number of SMTP connections that are reserved for connections from the
hosts that are specified in "smtp_reserve_hosts". The value set in
"smtp_accept_max" includes this reserve pool. For example, if
"smtp_accept_max" is set to 50 and "smtp_accept_reserve" is set to 5,
once there are 45 active connections, new ones are accepted only from
hosts listed in "smtp_reserve_hosts".


File: exim.info,  Node: smtp_banner,  Next: smtp_check_spool_space,  Prev: smtp_accept_reserve,  Up: Main configuration

smtp_banner _option_
--------------------

Type: string, expanded
Default: see below

This string, which is expanded every time it is used, is output as the
initial positive response to an SMTP connection. The default setting is:

     smtp_banner = $primary_hostname ESMTP Exim $version_number \
       #$compile_number $tod_full

Failure to expand the string causes a panic error. If you want to
create a multiline response to the initial SMTP connection, use `\n' in
the string at appropriate points, but not at the end.  Note that the
220 code is not included in this string. Exim adds it automatically
(several times in the case of a multiline response).


File: exim.info,  Node: smtp_check_spool_space,  Next: smtp_connect_backlog,  Prev: smtp_banner,  Up: Main configuration

smtp_check_spool_space _option_
-------------------------------

Type: boolean
Default: true

When this option is set, if an incoming SMTP session encounters the SIZE
option on a MAIL command, it checks that there is enough space in the
spool directory's partition to accept a message of that size, while
still leaving free the amount specified by "check_spool_space" (even if
that value is zero). If there isn't enough space, a temporary error
code is returned.


File: exim.info,  Node: smtp_connect_backlog,  Next: smtp_etrn_command,  Prev: smtp_check_spool_space,  Up: Main configuration

smtp_connect_backlog _option_
-----------------------------

Type: integer
Default: 5

This specifies a maximum number of waiting SMTP connections. Exim
passes this value to the TCP/IP system when it sets up its listener.
Once this number of connections are waiting for the daemon's attention,
subsequent connection attempts are refused at the TCP/IP level. At
least, that is what the manuals say. In Solaris 2.4 such connection
attempts have been observed to time out.  The default value of 5 is a
conservative one, suitable for older and smaller systems.  For large
systems is it probably a good idea to increase this, possibly
substantially (to 50, say). It also gives some protection against
denial-of-service attacks by SYN flooding.


File: exim.info,  Node: smtp_etrn_command,  Next: smtp_etrn_hosts,  Prev: smtp_connect_backlog,  Up: Main configuration

smtp_etrn_command _option_
--------------------------

Type: string, expanded
Default: unset

If this option is set, the given command is run whenever an SMTP ETRN
command is received from a host that is permitted to issue such
commands (see "smtp_etrn_hosts" below). The string is split up into
separate arguments which are independently expanded. The expansion
variable $domain is set to the argument of the ETRN command, and no
syntax checking is done on it. For example:

     smtp_etrn_command = /etc/etrn_command $domain $sender_host_address

A new process is created to run the command, and Exim does not wait for
it to complete. Consequently, its status cannot be checked.  If the
"exec" of the command fails, a line is written to the panic log, but the
ETRN caller still receives a 250 success response.  Exim is normally
running under its own uid when receiving SMTP, so it is not possible
for it to change the uid before running the command.

You must disable "smtp_etrn_serialize" if you use this option to run
something other than a call of Exim with the -R option, because
otherwise the serialization lock never gets removed.


File: exim.info,  Node: smtp_etrn_hosts,  Next: smtp_etrn_serialize,  Prev: smtp_etrn_command,  Up: Main configuration

smtp_etrn_hosts _option_
------------------------

Type: host list
Default: unset

This option lists hosts that are permitted to issue an SMTP ETRN to the
local host. See section "The ETRN command" in chapter "SMTP processing"
for details.


File: exim.info,  Node: smtp_etrn_serialize,  Next: smtp_expn_hosts,  Prev: smtp_etrn_hosts,  Up: Main configuration

smtp_etrn_serialize _option_
----------------------------

Type: boolean
Default: true

When this option is set, it prevents the simultaneous execution of more
than one queue run for the same argument string as a result of an ETRN
command.  See section "The ETRN command" in chapter "SMTP processing"
for details.


File: exim.info,  Node: smtp_expn_hosts,  Next: smtp_load_reserve,  Prev: smtp_etrn_serialize,  Up: Main configuration

smtp_expn_hosts _option_
------------------------

Type: host list
Default: unset

The SMTP EXPN command is supported only if the calling host matches
"smtp_expn_hosts". You must add `localhost' explicitly if you want
calls to 127.0.0.1 to be able to use it. A single-level expansion of
the address is done, as if the address were being tested using the -bt
option. If an unqualified local part is given, it is qualified with
"qualify_domain". There is a generic option for directors which permits
them to be skipped when processing an EXPN command (compare with
verification).


File: exim.info,  Node: smtp_load_reserve,  Next: smtp_receive_timeout,  Prev: smtp_expn_hosts,  Up: Main configuration

smtp_load_reserve _option_
--------------------------

Type: fixed-point
Default: unset

If the system load average ever gets higher than this, incoming SMTP
calls are accepted only from those hosts that match an entry in
"smtp_reserve_hosts".  If "smtp_reserve_hosts" is not set, no incoming
SMTP calls are accepted when the load is over the limit.  There are
some operating systems for which Exim cannot determine the load average
(see chapter 1); for these this option has no effect.


File: exim.info,  Node: smtp_receive_timeout,  Next: smtp_reserve_hosts,  Prev: smtp_load_reserve,  Up: Main configuration

smtp_receive_timeout _option_
-----------------------------

Type: time
Default: 5m

This sets a timeout value for SMTP reception. If a line of input
(either an SMTP command or a data line) is not received within this
time, the SMTP connection is dropped and the message is abandoned.  For
non-SMTP input, the reception timeout is controlled by "accept_timeout".


File: exim.info,  Node: smtp_reserve_hosts,  Next: smtp_verify,  Prev: smtp_receive_timeout,  Up: Main configuration

smtp_reserve_hosts _option_
---------------------------

Type: host list
Default: unset

This option defines hosts for which SMTP connections are reserved; see
"smtp_accept_reserve" and "smtp_load_reserve" above.


File: exim.info,  Node: smtp_verify,  Next: split_spool_directory,  Prev: smtp_reserve_hosts,  Up: Main configuration

smtp_verify _option_
--------------------

Type: boolean
Default: false

If this option is true, the SMTP command VRFY is supported on incoming
SMTP connections; otherwise it is not.


File: exim.info,  Node: split_spool_directory,  Next: spool_directory,  Prev: smtp_verify,  Up: Main configuration

split_spool_directory _option_
------------------------------

Type: boolean
Default: false

If this option is set, it causes Exim to split its input directory into
62 subdirectories, each with a single alphanumeric character as its
name. The sixth character of the message id is used to allocate
messages to subdirectories; this is the least significant base-62 digit
of the time of arrival of the message.

Splitting up the spool in this way may provide better performance on
systems where there are long mail queues, by reducing the number of
files in any one directory. The msglog directory is also split up in a
similar way to the input directory; however, if "preserve_message_logs"
is set, all old msglog files are still placed in the single directory
"msglog.OLD".

It is not necessary to take any special action for existing messages
when changing "split_spool_directory". Exim notices messages that are
in the `wrong' place, and continues to process them. If the option is
turned off after a period of being on, the subdirectories will
eventually empty and be automatically deleted.

When "split_spool_directory" is set, the behaviour of queue runner
processes changes. Instead of creating a list of all messages in the
queue, and then trying to deliver each one in turn, it constructs a
list of those in one sub-directory and tries to deliver them, before
moving on to the next sub-directory. The sub-directories are processed
in a random order. This spreads out the scanning of the input
directories, and is beneficial when there are lots of messages on the
queue. However, if "queue_run_in_order" is set, none of this new
processing happens. The entire queue is scanned and sorted before any
deliveries start.


File: exim.info,  Node: spool_directory,  Next: strip_excess_angle_brackets,  Prev: split_spool_directory,  Up: Main configuration

spool_directory _option_
------------------------

Type: string
Default: set at compile time

This defines the directory in which Exim keeps its mail spool. The
default value is taken from the compile-time configuration setting, if
there is one. If not, this option must be set. The string is expanded,
so it can contain, for example, a reference to $primary_hostname.

If the spool directory name is fixed on your installation, it is
recommended that you set it at build time rather than from this option,
particularly if the log files are being written to the spool directory
(see "log_file_path"). Otherwise log files cannot be used for errors
that are detected early on, such as failures in the configuration file.

Even with a compiled-in path, however, this option makes it possible to
run testing configurations of Exim without using the standard spool.


File: exim.info,  Node: strip_excess_angle_brackets,  Next: strip_trailing_dot,  Prev: spool_directory,  Up: Main configuration

strip_excess_angle_brackets _option_
------------------------------------

Type: boolean
Default: false

If this option is set, redundant pairs of angle brackets round
`route-addr' items in addresses are stripped. For example,
"<<xxx@a.b.c.d>>" is treated as "<xxx@a.b.c.d>". If this is in the
envelope and the message is passed on to another MTA, the excess angle
brackets are not passed on. If this option is not set, multiple pairs
of angle brackets cause a syntax error.


File: exim.info,  Node: strip_trailing_dot,  Next: syslog_timestamp,  Prev: strip_excess_angle_brackets,  Up: Main configuration

strip_trailing_dot _option_
---------------------------

Type: boolean
Default: false

If this option is set, a trailing dot at the end of a domain in an
address is ignored. If this is in the envelope and the message is
passed on to another MTA, the dot is not passed on. If this option is
not set, a dot at the end of a domain causes a syntax error.


File: exim.info,  Node: syslog_timestamp,  Next: timeout_frozen_after,  Prev: strip_trailing_dot,  Up: Main configuration

syslog_timestamp _option_
-------------------------

Type: boolean
Default: true

If "syslog_timestamp" is set false, the timestamps on Exim's log lines
are omitted when these lines are sent to syslog. See chapter "Log
files" for details of Exim's logging.


File: exim.info,  Node: timeout_frozen_after,  Next: timestamps_utc,  Prev: syslog_timestamp,  Up: Main configuration

timeout_frozen_after _option_
-----------------------------

Type: time
Default: 0s

If "timeout_frozen_after" is set to a time greater than zero, a frozen
message of any description that has been on the queue for longer than
the given time is automatically cancelled at the next queue run. If it
is a bounce message, it is just discarded; otherwise, a bounce is sent
to the sender, in a similar manner to cancellation by the -Mg command
line option. If you want to timeout frozen bounce messages earlier than
other kinds of frozen message, see "ignore_errmsg_errors_after".


File: exim.info,  Node: timestamps_utc,  Next: timezone,  Prev: timeout_frozen_after,  Up: Main configuration

timestamps_utc _option_
-----------------------

Type: boolean
Default: false

If "timestamps_utc" is set, all timestamps generated by Exim (for
example, in log entries and "Received:" header lines) are in UTC (aka
GMT) rather than in local wall-clock time.


File: exim.info,  Node: timezone,  Next: tls_advertise_hosts,  Prev: timestamps_utc,  Up: Main configuration

timezone _option_
-----------------

Type: string
Default: unset

When "timestamps_utc" is not set, the value of "timezone" is used to
set the environment variable TZ while running Exim (if it is different
on entry).  This ensures that all timestamps created by Exim are in the
required timezone.  The default value is taken from TIMEZONE_DEFAULT in
`Local/Makefile', or, if that is not set, from the value of the TZ
environment variable when Exim is built. If "timezone" is set to the
empty string, either at build or run time, then any existing TZ
variable is removed from the environment when Exim runs. This is
appropriate behaviour for obtaining wall-clock time on some, but
unfortunately not all, operating systems.


File: exim.info,  Node: tls_advertise_hosts,  Next: tls_certificate,  Prev: timezone,  Up: Main configuration

tls_advertise_hosts _option_
----------------------------

Type: host list
Default: unset

When Exim is built with support for TLS encrypted connections, the
availability of the STARTTLS command to set up an encrypted session is
advertised only to those client hosts that match this option. See
chapter "Encrypted SMTP connections using TLS/SSL" for details of
Exim's support for TLS.


File: exim.info,  Node: tls_certificate,  Next: tls_dhparam,  Prev: tls_advertise_hosts,  Up: Main configuration

tls_certificate _option_
------------------------

Type: string, expanded
Default: unset

The value of this option is expanded, and must then be the absolute
path to a file which contains the server's certificate.


File: exim.info,  Node: tls_dhparam,  Next: tls_host_accept_relay,  Prev: tls_certificate,  Up: Main configuration

tls_dhparam _option_
--------------------

Type: string, expanded
Default: unset

The value of this option is expanded, and must then be the absolute
path to a file which contains the server's DH parameter values.


File: exim.info,  Node: tls_host_accept_relay,  Next: tls_hosts,  Prev: tls_dhparam,  Up: Main configuration

tls_host_accept_relay _option_
------------------------------

Type: host list
Default: unset

Client hosts which match this list are allowed to relay, provided they
make use of TLS to send the message over an encrypted channel.


File: exim.info,  Node: tls_hosts,  Next: tls_log_cipher,  Prev: tls_host_accept_relay,  Up: Main configuration

tls_hosts _option_
------------------

Type: host list
Default: unset

Client hosts which match this list are required to use TLS to set up an
encrypted channel before Exim will accept any messages from them.


File: exim.info,  Node: tls_log_cipher,  Next: tls_log_peerdn,  Prev: tls_hosts,  Up: Main configuration

tls_log_cipher _option_
-----------------------

Type: boolean
Default: true

If this option is set, the cipher which was used to transmit a message
is logged using the tag `X='. This applies to both incoming and
outgoing messages.


File: exim.info,  Node: tls_log_peerdn,  Next: tls_privatekey,  Prev: tls_log_cipher,  Up: Main configuration

tls_log_peerdn _option_
-----------------------

Type: boolean
Default: false

If this option is set, the Distinguished Name of the server's
certificate is logged, using the tag `DN=', for all outgoing messages
delivered over TLS. For incoming messages, the DN from the client's
certificate is logged if a certificate was requested from the client
(see "tls_verify_certificates").


File: exim.info,  Node: tls_privatekey,  Next: tls_verify_certificates,  Prev: tls_log_peerdn,  Up: Main configuration

tls_privatekey _option_
-----------------------

Type: string, expanded
Default: unset

The value of this option is expanded, and must then be the absolute
path to a file which contains the server's private key.


File: exim.info,  Node: tls_verify_certificates,  Next: tls_verify_ciphers,  Prev: tls_privatekey,  Up: Main configuration

tls_verify_certificates _option_
--------------------------------

Type: string, expanded
Default: unset

The value of this option is expanded, and must then be the absolute
path to a file or a directory containing permitted certificates for
clients that match "tls_verify_hosts".


File: exim.info,  Node: tls_verify_ciphers,  Next: tls_verify_hosts,  Prev: tls_verify_certificates,  Up: Main configuration

tls_verify_ciphers _option_
---------------------------

Type: string, expanded
Default: unset

The value of this option is expanded, and must then be a
colon-separated list of permitted ciphers for the clients that match
"tls_verify_hosts". Exim's syntax for alternate separator characters
cannot be used for this list, because it is passed directly to the SSL
library.


File: exim.info,  Node: tls_verify_hosts,  Next: trusted_groups,  Prev: tls_verify_ciphers,  Up: Main configuration

tls_verify_hosts _option_
-------------------------

Type: host list
Default: unset

Any client that matches this list is constrained by
"tls_verify_certificates" and "tls_verify_ciphers", that is, it must
use one of the permitted ciphers, and present one of the listed
certificates. Client hosts that do not match the list are not so
constrained.


File: exim.info,  Node: trusted_groups,  Next: trusted_users,  Prev: tls_verify_hosts,  Up: Main configuration

trusted_groups _option_
-----------------------

Type: string list
Default: unset

If this option is set, any process that is running in one of the listed
groups, or which has one of them as a supplementary group, is trusted.
See section "Trusted and admin users" in chapter "The Exim command
line" for details of what trusted callers are permitted to do. If
neither "trusted_groups" nor "trusted_users" is set, only root and the
Exim user are trusted.


File: exim.info,  Node: trusted_users,  Next: unknown_login,  Prev: trusted_groups,  Up: Main configuration

trusted_users _option_
----------------------

Type: string list
Default: unset

If this option is set, any process that is running as one of the listed
users is trusted. See section "Trusted and admin users" in chapter "The
Exim command line" for details of what trusted callers are permitted to
do. If neither "trusted_groups" nor "trusted_users" is set, only root
and the Exim user are trusted.


File: exim.info,  Node: unknown_login,  Next: unknown_username,  Prev: trusted_users,  Up: Main configuration

unknown_login _option_
----------------------

Type: string
Default: unset

This is a specialized feature for use in unusual configurations. By
default, if the uid of the caller of Exim cannot be looked up using
"getpwuid()", Exim gives up. The "unknown_login" option can be used to
set a login name to be used in this circumstance. It is expanded, so
values like "user$caller_uid" can be set. When "unknown_login" is used,
the value of "unknown_username" is used for the user's real name (gecos
field), unless this has been set by the -F option.


File: exim.info,  Node: unknown_username,  Next: untrusted_set_sender,  Prev: unknown_login,  Up: Main configuration

unknown_username _option_
-------------------------

Type: string
Default: unset

See "unknown_login".


File: exim.info,  Node: untrusted_set_sender,  Next: uucp_from_pattern,  Prev: unknown_username,  Up: Main configuration

untrusted_set_sender _option_
-----------------------------

Type: boolean
Default: false

By default, the only form in which untrusted users can use the -f
command line option when submitting a local message is with an empty
address, to declare that a message should never generate any bounces. If
"untrusted_set_sender" is true, this restriction is lifted, and
untrusted users may set any sender value using -f. This does not make
all users trusted; they may use only -f, not the other options which
override message parameters. Furthermore, this does not stop Exim from
adding a "Sender:" header if necessary (unless this is disabled by
"no_local_from_check").

The log line for a message's arrival shows the envelope sender
following `<='.  For local messages, the user's login always follows,
after `U='.  In -bp displays, and in the Exim monitor, if an untrusted
user sets a sender address by this method, the user's login is shown in
parentheses after the sender address.


File: exim.info,  Node: uucp_from_pattern,  Next: uucp_from_sender,  Prev: untrusted_set_sender,  Up: Main configuration

uucp_from_pattern _option_
--------------------------

Type: string
Default: see below

Some applications that pass messages to an MTA via a command line
interface use an initial line starting with `From' to pass the envelope
sender. In particular, this is used by UUCP software. Exim recognizes
such a line by means of a regular expression that is set in
"uucp_from_pattern", and when the pattern matches, the sender address
is constructed by expanding the contents of "uucp_from_sender",
provided that the caller of Exim is a trusted user. The default pattern
recognizes lines in the following two forms:

        From ph10 Fri Jan  5 12:35 GMT 1996
        From ph10 Fri, 7 Jan 97 14:00:00 GMT

The pattern can be seen by running `exim -bP uucp_from_pattern'.  It
checks only up to the hours and minutes, and allows for a 2-digit or
4-digit year in the second case. The first word after `From' is matched
in the regular expression by a parenthesized subpattern. The default
value for "uucp_from_sender" is `$1', which therefore just uses this
first word (`ph10' in the example above) as the message's sender.  See
also "ignore_fromline_hosts".


File: exim.info,  Node: uucp_from_sender,  Next: warnmsg_file,  Prev: uucp_from_pattern,  Up: Main configuration

uucp_from_sender _option_
-------------------------

Type: string, expanded
Default: "$1"

See "uucp_from_pattern" above.


File: exim.info,  Node: warnmsg_file,  Prev: uucp_from_sender,  Up: Main configuration

warnmsg_file _option_
---------------------

Type: string
Default: unset

This option defines a template file containing paragraphs of text to be
used for constructing the warning message which is sent by Exim when a
message has been on the queue for a specified amount of time, as
specified by "delay_warning". Details of the file's contents are given
in chapter "Customizing error and warning messages". See also
"errmsg_file".


File: exim.info,  Node: Driver specifications,  Next: Environment for running local transports,  Prev: Main configuration,  Up: Top

Driver specifications
*********************

The second, third, and fourth parts of Exim's configuration file
specify which transport, director, and router drivers are to be used.
Directors and routers are similar, in that an address is passed to a
list of them in the order in which they are defined, whereas the order
in which transports are specified is immaterial, because a transport is
invoked only after being passed an address by a director or a router.
Section "Drivers" in chapter "How Exim delivers mail" discusses how the
different kinds of delivery driver interact.

The seventh part of the configuration file (if present) specifies the
authenticators that are to be used for SMTP connections (see chapter
"SMTP authentication"). These are a somewhat different kind of `driver'
to the others, but they are configured in a similar way.

The format of the configuration data is the same for all four types of
driver, and is as follows:

     <instance name>:
       <option>
       ...
       <option>

There are two kinds of option: generic and private. The generic options
are those that apply to all drivers of the same type (that is, all
directors, all routers, all transports or all authenticators).  There
is always at least one generic option, called "driver", which specifies
which particular driver is being used.  The private options are
particular to each driver, and none need appear.

The options may appear in any order, except that the "driver" option
must precede any private options, since these depend on the particular
driver. For this reason, it is recommended that "driver" always be the
first option.

In earlier versions of Exim, commas were used between options, and the
generic options had to precede the private ones and be terminated by a
semicolon. This has not been the case for some time, and at release
3.00 the backwards-compatibility code for ignoring commas and
semicolons was removed.

Each instance of a driver is given an identifying "instance name" name
for reference in logging and elsewhere. The name can be any sequence of
letters, digits, and underscores (starting with a letter) and must be
unique among drivers of the same type. A router and a transport (for
example) can each have the same name, but no two router instances can
have the same name. The name of a driver instance should not be
confused with the name of the underlying driver. The configuration lines

     remote_smtp:
       driver = smtp

create an instance of the "smtp" transport driver whose name is
"remote_smtp".  The same driver code can be used more than once, with
different instance names and different option settings each time. A
second instance of the "smtp" transport, with different options, might
be defined thus:

     special_smtp:
       driver = smtp
       port = 1234
       command_timeout = 10s

The names "remote_smtp" and "special_smtp" would be used to reference
these driver instances from directors or routers, and would appear in
log lines.

Comment lines may appear in the middle of driver specifications. The
full list of option settings for any particular driver instance,
including all the defaults, can be extracted by making use of the -bP
command line option (see chapter "The Exim command line").

The next chapter describes the environment in which local deliveries
are done, and how this is affected by the configurations of the
relevant directors, routers, and transports. Then there is a chapter
describing the generic options for transports, followed by descriptions
of the available transport drivers.  Directors and routers have some
generic options in common, and these are covered in chapter "Generic
options common to both directors and routers" before the descriptions
of the generic options that are specific to each type of driver, and
the drivers themselves.  The SMTP AUTH mechanism for client
authentication is described in chapter "SMTP authentication", which is
followed by descriptions of the available authenticators.


File: exim.info,  Node: Environment for running local transports,  Next: Generic options for transports,  Prev: Driver specifications,  Up: Top

Environment for running local transports
****************************************

Local transports handle deliveries to files and pipes. (The "autoreply"
transport can be thought of as similar to a pipe.) Whenever a local
transport is run, Exim forks a subprocess for it.  Before running the
transport code, it sets a specific uid and gid by calling "setuid()"
and "setgid()". It also sets a current file directory; for some
transports a home directory setting is also relevant.  The "pipe"
transport is the only one which sets up environment variables; see
section "Environment variables" in chapter "The pipe transport" for
details.

The values used for the uid, gid, and the directories may come from
several different places. In many cases the director that handles the
address associates settings with that address. However, values may also
be given in the transport's own configuration, and these override
anything that comes with the address. The sections below contain a
summary of the possible sources of the values, and how they interact
with each other.



* Menu:

* Uids and gids::
* Current and home directories::
* Expansion variables derived from the address::


File: exim.info,  Node: Uids and gids,  Next: Current and home directories,  Prev: Environment for running local transports,  Up: Environment for running local transports

Uids and gids
=============

All local transports have the options "group" and "user". If "group" is
set, it overrides any group that may be set in the address, even if
"user" is not set.  This makes it possible, for example, to run local
mail delivery under the uid of the recipient, but in a special group.
For example:

     group_delivery:
       driver = appendfile
       file = /var/spool/mail/$local_part
       group = mail

If "user" is set for a transport, its value overrides what is set in the
address. If "user" is non-numeric and "group" is not set, the gid
associated with the user is used. If "user" is numeric, "group" must be
set.

The "pipe" transport contains the special option "pipe_as_creator". If
this is set and "user" is not set, the uid of the process that called
Exim to receive the message is used, and if "group" is not set, the
corresponding original gid is also used.

When the uid is taken from the transport's configuration, the
"initgroups()" function is called for the groups associated with that
uid if the "initgroups" option is set for the transport; "pipe" is the
only transport that has such an option.

When the uid is not specified by the transport, but is associated with
the address by a director or router, the option for calling
"initgroups()" is taken from the director or router configuration. All
directors and routers have "group", "user", and "initgroups" options,
which are used as follows:

For the "aliasfile" director they specify the uid and gid for local
deliveries generated directly - that is, deliveries to pipes or files.
They have no effect on generated addresses that are processed
independently.

The "forwardfile" director's "check_local_user" option causes a
password file lookup for the local part of an address. The uid and gid
obtained from this lookup are used for any directly generated local
deliveries, but they can be overridden by the "group" and "user"
options of the director. As for "aliasfile", these values are not used
for generated addresses that are processed independently.

The "localuser" director looks up local parts in the password file, and
sets the uid and gid from that file for local deliveries, but these
values can be overridden by the director's options.

For the "smartuser" director and all the routers, the "group", "user",
and "initgroups" options are used only if the driver sets up a delivery
to a local transport.


File: exim.info,  Node: Current and home directories,  Next: Expansion variables derived from the address,  Prev: Uids and gids,  Up: Environment for running local transports

Current and home directories
============================

The "pipe" transport has a "home_directory" option. If this is set, it
overrides any home directory set by the director for the address. The
value of the home directory is set in the environment variable HOME
while running the pipe. It need not be set, in which case HOME is not
defined.

The "appendfile" transport does not have a "home_directory" option. The
only uses for a home directory in this transport are the appearance of
the expansion variable $home in one of its options, and the `inhome' or
`belowhome' settings of the "create_file" option. In both cases the
value set by the director is used.

The "appendfile" and "pipe" transports have a "current_directory"
option. If this is set, it overrides any current directory set by the
director for the address. If neither the director nor the transport
sets a current directory, then Exim uses the value of the home
directory, if set. Otherwise it sets the current directory to `/'
before running a local transport.

All directors have "current_directory" and "home_directory" options,
which are associated with any addresses they explicitly direct to a
local transport.

For "forwardfile", if "home_directory" is not set and there is a
"file_directory" value, that is used instead. If it too is not set, but
"check_local_user" is set, the user's home directory is used. For
"localuser", if "home_directory" is not set, the home directory is
taken from the password file entry that this director looks up. There
are no defaults for "current_directory" in the directors, because it
defaults to the value of "home_directory" if it is not set at transport
time.

Routers have no means of setting up home and current directory strings;
consequently any local transport that they use must specify them for
itself if they are required.


File: exim.info,  Node: Expansion variables derived from the address,  Prev: Current and home directories,  Up: Environment for running local transports

Expansion variables derived from the address
============================================

Normally a local delivery is handling a single address, and in that
case the variables such as $domain and $local_part are set during local
deliveries. However, in some circumstances more than one address may be
handled at once (for example, while writing batch SMTP for onward
transmission by some other means). In this case, the variables
associated with the local part are never set, $domain is set only if
all the addresses have the same domain, and $original_domain is never
set.


File: exim.info,  Node: Generic options for transports,  Next: The appendfile transport,  Prev: Environment for running local transports,  Up: Top

Generic options for transports
******************************

The generic options for transports are as follows:



* Menu:

* body_only (transport)::
* debug_print (transport)::
* delivery_date_add (transport)::
* driver (transport)::
* envelope_to_add (transport)::
* headers_add (transport)::
* headers_only (transport)::
* headers_remove (transport)::
* headers_rewrite (transport)::
* message_size_limit (transport)::
* return_path (transport)::
* return_path_add (transport)::
* shadow_condition (transport)::
* shadow_transport (transport)::
* transport_filter (transport)::


File: exim.info,  Node: body_only (transport),  Next: debug_print (transport),  Prev: Generic options for transports,  Up: Generic options for transports

body_only (transport) _option_
------------------------------

Type: boolean
Default: false

If this option is set, the message's headers are not transported. It is
mutually exclusive with "headers_only". If it is used with the
"appendfile" or "pipe" transports, the settings of "prefix" and
"suffix" should be checked, since this option does not automatically
suppress them.


File: exim.info,  Node: debug_print (transport),  Next: delivery_date_add (transport),  Prev: body_only (transport),  Up: Generic options for transports

debug_print (transport) _option_
--------------------------------

Type: string
Default: unset

If this option is set and debugging is enabled (see -d, -v, and
"debug_level"), the string is expanded and included in the debugging
output when the transport is run. This is to help with checking out the
values of variables and so on when debugging driver configurations. For
example, if a "headers_add" option is not working properly,
"debug_print" could be used to output the variables it references. A
newline is added to the text if it does not end with one.


File: exim.info,  Node: delivery_date_add (transport),  Next: driver (transport),  Prev: debug_print (transport),  Up: Generic options for transports

delivery_date_add (transport) _option_
--------------------------------------

Type: boolean
Default: false

If this option is true, a "Delivery-date:" header is added to the
message. This gives the actual time the delivery was made. As this is
not a standard header, Exim has a configuration option
("delivery_date_remove") which requests its removal from incoming
messages, so that delivered messages can safely be resent to other
recipients.


File: exim.info,  Node: driver (transport),  Next: envelope_to_add (transport),  Prev: delivery_date_add (transport),  Up: Generic options for transports

driver (transport) _option_
---------------------------

Type: string
Default: unset

This specifies which of the available transport drivers is to be used.
For example:

     driver = smtp

There is no default, and this option must be set for every transport.


File: exim.info,  Node: envelope_to_add (transport),  Next: headers_add (transport),  Prev: driver (transport),  Up: Generic options for transports

envelope_to_add (transport) _option_
------------------------------------

Type: boolean
Default: false

If this option is true, an "Envelope-to:" header is added to the
message. This gives the original address(es) in the incoming envelope
that caused this delivery to happen. More than one address may be
present if "batch" or "bsmtp" is set on transports that support them,
or if more than one original address was aliased or forwarded to the
same final address. As this is not a standard header, Exim has a
configuration option ("envelope_to_remove") which requests its removal
from incoming messages, so that delivered messages can safely be resent
to other recipients.


File: exim.info,  Node: headers_add (transport),  Next: headers_only (transport),  Prev: envelope_to_add (transport),  Up: Generic options for transports

headers_add (transport) _option_
--------------------------------

Type: string
Default: unset

This option specifies a string of text which is expanded and added to
the header portion of a message as it is transported.  If the result of
the expansion is an empty string, or if the expansion is forced to
fail, no action is taken. Other expansion failures are treated as
errors and cause the delivery to be deferred.  The expanded string
should be in the form of one or more RFC 822 header lines, separated by
newlines (coded as `\n' inside a quoted string), for example:

     headers_add = "X-added: this is a header added at $tod_log\n\
                    X-added: this is another"

Exim does not check the syntax of these added headers. A newline is
supplied at the end if one is not present. The text is added at the end
of any existing headers. If you include a blank line within the string,
you can subvert this facility into adding text at the start of the
message's body.

The name "add_headers" was formerly used for this option, and is
retained as a synonym for backward compatibility. Additional headers
can also be specified by directors and routers. See chapter "Generic
options common to both directors and routers" and section "Adding and
removing headers" in chapter "Message processing".


File: exim.info,  Node: headers_only (transport),  Next: headers_remove (transport),  Prev: headers_add (transport),  Up: Generic options for transports

headers_only (transport) _option_
---------------------------------

Type: boolean
Default: false

If this option is set, the message's body is not transported. It is
mutually exclusive with "body_only". If it is used with the
"appendfile" or "pipe" transports, the settings of "prefix" and
"suffix" should be checked, since this option does not automatically
suppress them.


File: exim.info,  Node: headers_remove (transport),  Next: headers_rewrite (transport),  Prev: headers_only (transport),  Up: Generic options for transports

headers_remove (transport) _option_
-----------------------------------

Type: string
Default: unset

This option is expanded; the result must consist of a colon-separated
list of header names, not including the terminating colon, for example:

     headers_remove = return-receipt-to:acknowledge-to

Any existing headers matching those names are not included in any
message that transmitted by the transport. However, added headers may
have these names.  Thus it is possible to replace a header by
specifying it in "headers_remove" and supplying the replacement in
"add_headers".

The name "remove_headers" was formerly used for this option, and is
retained as a synonym for backward compatibility. Headers to be removed
can also be specified by directors and routers. See chapter "Generic
options common to both directors and routers" and section "Adding and
removing headers" in chapter "Message processing".


File: exim.info,  Node: headers_rewrite (transport),  Next: message_size_limit (transport),  Prev: headers_remove (transport),  Up: Generic options for transports

headers_rewrite (transport) _option_
------------------------------------

Type: string
Default: unset

This option allows addresses in header lines to be rewritten at
transport time, that is, as the message is being copied to its
destination. The contents of the option are a colon-separated list of
rewriting rules. Each rule is in exactly the same form as one of the
general rewriting rules that are applied when a message is received.
These are described in chapter "Address rewriting". For example,

     headers_rewrite = a@b c@d f : \
                       x@y w@z

changes "a@b" into "c@d" in "From:" header lines, and "x@y" into "w@z"
in all address-bearing header lines. The rules are applied to the
header lines just before they are  written out at transport time, so
they affect only those copies of the message that pass through the
transport. However, only the message's original header lines, and any
that were added by a system filter, are rewritten. If a router,
director, or transport adds header lines, these are not affected. These
rewriting rules are not applied to the envelope. You can change the
return path using "return_path"; you cannot change envelope recipients
at this time.


File: exim.info,  Node: message_size_limit (transport),  Next: return_path (transport),  Prev: headers_rewrite (transport),  Up: Generic options for transports

message_size_limit (transport) _option_
---------------------------------------

Type: integer
Default: 0

This option controls the size of messages passed through the transport.
If its value is greater than zero and the size of a message message
exceeds the limit, the address is failed. If there is any chance that
the resulting bounce message could be routed to the same transport, you
should ensure that "return_size_limit" is less than the transport's
"message_size_limit", as otherwise the bounce message will fail to get
delivered.


File: exim.info,  Node: return_path (transport),  Next: return_path_add (transport),  Prev: message_size_limit (transport),  Up: Generic options for transports

return_path (transport) _option_
--------------------------------

Type: string, expanded
Default: unset

If this option is set, the string is expanded at transport time and
replaces the existing return path (envelope sender) value. The
expansion can refer to the existing value via $return_path. If the
expansion is forced to fail, no replacement occurs; if it fails for
another reason, Exim panics. This option can be used to support VERP
(Variable Envelope Return Paths) - see chapter "SMTP processing".


File: exim.info,  Node: return_path_add (transport),  Next: shadow_condition (transport),  Prev: return_path (transport),  Up: Generic options for transports

return_path_add (transport) _option_
------------------------------------

Type: boolean
Default: false

If this option is true, a "Return-path:" header is added to the
message. Although the return path is normally available in the prefix
line of BSD mailboxes, this is commonly not displayed by MUAs, and so
the user does not have easy access to it.

RFC 822 states that the "Return-path:" header is `added by the final
transport system that delivers the message to its recipient' (section
4.3.1), which implies that this header should not be present in
incoming messages. Exim has a configuration option,
"return_path_remove", which requests removal of this header from
incoming messages, so that delivered messages can safely be resent to
other recipients.


File: exim.info,  Node: shadow_condition (transport),  Next: shadow_transport (transport),  Prev: return_path_add (transport),  Up: Generic options for transports

shadow_condition (transport) _option_
-------------------------------------

Type: string, expanded
Default: unset

See "shadow_transport" below.


File: exim.info,  Node: shadow_transport (transport),  Next: transport_filter (transport),  Prev: shadow_condition (transport),  Up: Generic options for transports

shadow_transport (transport) _option_
-------------------------------------

Type: string
Default: unset

This facility is somewhat experimental, and may change in future. A
local transport may set the "shadow_transport" option to the name of
another, previously-defined, local transport. Shadow remote transports
are not supported.

Whenever a delivery to the main transport succeeds, and either
"shadow_condition" is unset, or its expansion does not result in a
forced expansion failure or the empty string or one of the strings `0'
or `no' or `false', the message is also passed to the shadow transport,
with the same delivery address or addresses.  However, the result of
the shadow transport is discarded and does not affect the subsequent
processing of the message. Only a single level of shadowing is
provided; the "shadow_transport" option is ignored on any transport
when it is running as a shadow. Options concerned with output from
pipes are also ignored.

The log line for the successful delivery has an item added on the end,
of the form

     ST=<shadow transport name>

If the shadow transport did not succeed, the error message is put in
parentheses afterwards.

Shadow transports can be used for a number of different purposes,
including keeping more detailed log information than Exim normally
provides, and implementing automatic acknowledgement policies based on
message headers that some sites insist on.


File: exim.info,  Node: transport_filter (transport),  Prev: shadow_transport (transport),  Up: Generic options for transports

transport_filter (transport) _option_
-------------------------------------

Type: string
Default: unset

This option sets up a filtering (in the Unix shell sense) process for
messages at transport time. It should not be confused with mail
filtering as set up by individual users or via a system filter.

When the message is about to be written out, the command specified by
"transport_filter" is started up in a separate process, and the entire
message, including the headers, is passed to it on its standard input
(this in fact is done from a third process, to avoid deadlock). This
happens before any SMTP-specific processing, such as turning `\n' into
`\r\n' and escaping lines beginning with a dot, and also before any
processing implied by the settings of "check_string" and
"escape_string" in the "appendfile" or "pipe" transports.

The filter's standard output is read and written to the message's
destination.  The filter can perform any transformations it likes, but
of course should take care not to break RFC 822 syntax. A demonstration
Perl script is provided in "util/transport-filter.pl"; this makes a few
arbitrary modifications just to show the possibilities.  Exim does not
check the result, except to test for a final newline when SMTP is in
use. All messages transmitted over SMTP must end with a newline, so Exim
supplies one if it is missing.

A problem might arise if the filter increases the size of a message
that is being sent down an SMTP channel. If the receiving SMTP server
has indicated support for the SIZE parameter, Exim will have sent the
size of the message at the start of the SMTP session. If what is
actually sent is substantially more, the server might reject the
message. This can be worked round by setting the "size_addition" option
on the "smtp" transport, either to allow for additions to the message,
or to disable the use of SIZE altogether.

The value of the option is the command string for starting up the
filter, which is run directly from Exim, not under a shell. The string
is parsed by Exim in the same way as a command string for the "pipe"
transport: Exim breaks it up into arguments and then expands each
argument separately. The special argument $pipe_addresses is replaced
by a number of arguments, one for each address that applies to this
delivery. (This isn't an ideal name for this feature here, but as it
was already implemented for the "pipe" transport, it seemed sensible
not to change it.)

The expansion variables $host and $host_address are available when the
transport is a remote one. They are set only for the expansion of a
transport filter command, as that is the only thing that is expanded
after a connection has been set up. For example:

     transport_filter = /some/directory/transport-filter.pl \
       $host $host_address $sender_address $pipe_addresses

The filter process is run under the same uid and gid as the normal
delivery.  For remote deliveries this is the exim uid/gid if they are
defined.

If a transport filter is set on an autoreply transport, the original
message is passed through the filter as it is being copied into the
newly generated message, which happens if the "return_message" option
is set.


File: exim.info,  Node: The appendfile transport,  Next: The autoreply transport,  Prev: Generic options for transports,  Up: Top

The appendfile transport
************************

The "appendfile" transport delivers a message by appending it to a file
in the local file system, or by creating an entirely new file in a
specified directory. Single files to which messages are appended can be
in the traditional Unix mailbox format, or optionally in the MBX format
supported by the Pine MUA and University of Washington IMAP daemon,
inter alia. When each message is being delivered as a separate file,
`maildir' format can optionally be used to give added protection
against failures that happen part-way through the delivery. A third
form of separate-file delivery known as `mailstore' is also supported.
For all file formats, Exim attempts to create as many levels of
directory as necessary, provided that "create_directory" is set.

The code for the optional formats is not included in the Exim binary by
default. It is necessary to set SUPPORT_MBX, SUPPORT_MAILDIR and/or
SUPPORT_MAILSTORE in `Local/Makefile' to have the appropriate code
included.

"Appendfile" can be used by routers as a pseudo-remote transport for
putting messages into files for remote delivery by some means other
than Exim, though it is more commonly used by directors for local
deliveries to users' mailboxes.  It is also used for delivering
messages to files or directories whose names are obtained directly from
alias, forwarding, or filtering operations. In these cases, $local_part
contains the local part that was aliased or forwarded, while
$address_file contains the name of the file or directory.

As "appendfile" is a local transport, it is always run in a separate
process, under a non-privileged uid and gid, which are set by
"setuid()". In the common local delivery case, these are the uid and
gid belonging to the user to whom the mail is being delivered. The
current directory is also normally set to the user's home directory.
See chapter "Environment for running local transports" for a discussion
of the local delivery environment.

If the transport fails for any reason, the message remains on the input
queue so that there can be another delivery attempt later. If there is
an error while appending to a file (for example, quota exceeded or
partition filled), Exim attempts to reset the file's length and last
modification time back to what they were before. Exim supports a local
quota, for use when the system facility is unavailable or cannot be
used for some reason.

Before appending to a file, a number of security checks are made, and
the file is locked. A detailed description is given below, after the
list of private options.



* Menu:

* Private options for appendfile::
* Operational details for appending::
* Operational details for delivery to a new file::


File: exim.info,  Node: Private options for appendfile,  Next: Operational details for appending,  Prev: The appendfile transport,  Up: The appendfile transport

Private options for appendfile
==============================



* Menu:

* allow_fifo (appendfile)::
* allow_symlink (appendfile)::
* batch (appendfile)::
* batch_max (appendfile)::
* bsmtp (appendfile)::
* bsmtp_helo (appendfile)::
* check_group (appendfile)::
* check_owner (appendfile)::
* check_string (appendfile)::
* create_directory (appendfile)::
* create_file (appendfile)::
* current_directory (appendfile)::
* directory (appendfile)::
* directory_mode (appendfile)::
* escape_string (appendfile)::
* file (appendfile)::
* file_format (appendfile)::
* file_must_exist (appendfile)::
* from_hack (appendfile)::
* group (appendfile)::
* lock_fcntl_timeout (appendfile)::
* lock_interval (appendfile)::
* lock_retries (appendfile)::
* lockfile_mode (appendfile)::
* lockfile_timeout (appendfile)::
* maildir_format (appendfile)::
* maildir_retries (appendfile)::
* maildir_tag (appendfile)::
* mailstore_format (appendfile)::
* mailstore_prefix (appendfile)::
* mailstore_suffix (appendfile)::
* mbx_format (appendfile)::
* mode (appendfile)::
* mode_fail_narrower (appendfile)::
* notify_comsat (appendfile)::
* prefix (appendfile)::
* quota (appendfile)::
* quota_filecount (appendfile)::
* quota_is_inclusive (appendfile)::
* quota_size_regex (appendfile)::
* quota_warn_message (appendfile)::
* quota_warn_threshold (appendfile)::
* require_lockfile (appendfile)::
* retry_use_local_part (appendfile)::
* suffix (appendfile)::
* use_crlf (appendfile)::
* use_fcntl_lock (appendfile)::
* use_lockfile (appendfile)::
* use_mbx_lock (appendfile)::
* user (appendfile)::


File: exim.info,  Node: allow_fifo (appendfile),  Next: allow_symlink (appendfile),  Prev: Private options for appendfile,  Up: Private options for appendfile

allow_fifo (appendfile) _option_
--------------------------------

Type: boolean
Default: false

Setting this option permits delivery to named pipes (FIFOs) as well as
to regular files. If no process is reading the named pipe at delivery
time, the delivery is deferred.


File: exim.info,  Node: allow_symlink (appendfile),  Next: batch (appendfile),  Prev: allow_fifo (appendfile),  Up: Private options for appendfile

allow_symlink (appendfile) _option_
-----------------------------------

Type: boolean
Default: false

By default, "appendfile" will not deliver if the path name for the file
is that of a symbolic link. Setting this option relaxes that
constraint, but there are security issues involved in the use of
symbolic links. Be sure you know what you are doing if you set this.
Details of exactly what this option affects are included in the
discussion which follows this list of options.


File: exim.info,  Node: batch (appendfile),  Next: batch_max (appendfile),  Prev: allow_symlink (appendfile),  Up: Private options for appendfile

batch (appendfile) _option_
---------------------------

Type: string
Default: "none"

Normally, each address that is directed or routed to an "appendfile"
transport is handled separately. In special cases it may be desirable
to handle several addresses at once, for example, when passing a
message with several addresses to a different mail regime (for example,
UUCP), though this is more often done using the "pipe" transport. If
this option is set to the string `domain', all addresses with the same
domain that are directed or routed to the transport are handled in a
single delivery. If it is set to `all' then multiple domains are
batched. The list of addresses is included in the "Envelope-to:" header
if the generic "envelope_to_add" option is set.  When more than one
address is being delivered, $local_part is not set, and $domain is set
only if they all have the same domain.  The only difference between
this option and "bsmtp" is the inclusion of SMTP command lines in the
output for "bsmtp", and the escaping of lines that begin with a full
stop (period).


File: exim.info,  Node: batch_max (appendfile),  Next: bsmtp (appendfile),  Prev: batch (appendfile),  Up: Private options for appendfile

batch_max (appendfile) _option_
-------------------------------

Type: integer
Default: 100

This limits the number of addresses that can be handled in a batch, and
applies to both the "batch" and the "bsmtp" options.


File: exim.info,  Node: bsmtp (appendfile),  Next: bsmtp_helo (appendfile),  Prev: batch_max (appendfile),  Up: Private options for appendfile

bsmtp (appendfile) _option_
---------------------------

Type: string
Default: "none"

This option is used to set up an "appendfile" transport as a
pseudo-remote transport for delivering messages into local files in
batch SMTP format for onward transmission by some non-Exim means. It is
usually necessary to suppress the default settings of the "prefix" and
"suffix" options when using batch SMTP.  The "check_string" and
"escape_string" options are forced to the values

     check_string = "."
     escape_string = ".."

when batched SMTP is in use.  The value of "bsmtp" must be one of the
strings `none', `one', `domain', or `all'. The first of these turns the
feature off. A full description of the batch SMTP mechanism is given in
section "Outgoing batched SMTP" in chapter "SMTP processing". When
"bstmp" is set, the "batch" option automatically takes the same value.
See also the "use_crlf" option.


File: exim.info,  Node: bsmtp_helo (appendfile),  Next: check_group (appendfile),  Prev: bsmtp (appendfile),  Up: Private options for appendfile

bsmtp_helo (appendfile) _option_
--------------------------------

Type: boolean
Default: false

When this option is set, a HELO line is added to the output at the
start of each message written in batch SMTP format. Some software that
reads batch SMTP is unhappy without this.


File: exim.info,  Node: check_group (appendfile),  Next: check_owner (appendfile),  Prev: bsmtp_helo (appendfile),  Up: Private options for appendfile

check_group (appendfile) _option_
---------------------------------

Type: boolean
Default: false

The group owner of the file is checked to see that it is the same as
the group under which the delivery process is running when this option
is set. The default setting is false because the default file mode is
0600, which means that the group is irrelevant.


File: exim.info,  Node: check_owner (appendfile),  Next: check_string (appendfile),  Prev: check_group (appendfile),  Up: Private options for appendfile

check_owner (appendfile) _option_
---------------------------------

Type: boolean
Default: true

The owner of the file is checked to ensure that it is the same as the
user under which the delivery process is running when this option is
set.


File: exim.info,  Node: check_string (appendfile),  Next: create_directory (appendfile),  Prev: check_owner (appendfile),  Up: Private options for appendfile

check_string (appendfile) _option_
----------------------------------

Type: string
Default: "From "

As "appendfile" writes the message, the start of each line is tested for
matching "check_string", and if it does, the initial matching
characters are replaced by the contents of "escape_string". The value
of "check_string" is a literal string, not a regular expression, and
the case of any letters it contains is significant.  For backwards
compatibility, if "no_from_hack" is specified, the values of
"check_string" and "escape_string" are forced to be unset.

The default settings, along with "prefix" and "suffix", are suitable for
traditional `BSD' mailboxes, where a line beginning with `From '
indicates the start of a new message. All four options need changing if
another format is used. For example, to deliver to mailboxes in MMDF
format:

     check_string = "\1\1\1\1\n"
     escape_string = "\1\1\1\1 \n"
     prefix = "\1\1\1\1\n"
     suffix = "\1\1\1\1\n"

When the "bsmtp" option is set, the contents of "check_string" and
"escape_string" are forced to values that implement the SMTP escaping
protocol. Any settings made in the configuration file are ignored.


File: exim.info,  Node: create_directory (appendfile),  Next: create_file (appendfile),  Prev: check_string (appendfile),  Up: Private options for appendfile

create_directory (appendfile) _option_
--------------------------------------

Type: boolean
Default: true

When this option is true, Exim creates any missing superior directories
for the file that it is about to write. A created directory's mode is
given by the "directory_mode" option.


File: exim.info,  Node: create_file (appendfile),  Next: current_directory (appendfile),  Prev: create_directory (appendfile),  Up: Private options for appendfile

create_file (appendfile) _option_
---------------------------------

Type: string
Default: "anywhere"

This option constrains the location of files that are created by this
transport. It must be set to one of the words `anywhere', `inhome', or
`belowhome'. In the second and third cases, a home directory must have
been set up for the address by the director that handled it. This
option isn't useful when an explicit file name is given for normal
mailbox deliveries; it is intended for the case when file names have
been generated from user's `.forward' files, which are usually handled
by an "appendfile" transport called "address_file". See also
"file_must_exist".


File: exim.info,  Node: current_directory (appendfile),  Next: directory (appendfile),  Prev: create_file (appendfile),  Up: Private options for appendfile

current_directory (appendfile) _option_
---------------------------------------

Type: string, expanded
Default: unset

If this option is set, it specifies the directory to make current when
running the delivery process. The string is expanded at the time the
transport is run.  See chapter "Environment for running local
transports" for details of the local delivery environment.


File: exim.info,  Node: directory (appendfile),  Next: directory_mode (appendfile),  Prev: current_directory (appendfile),  Up: Private options for appendfile

directory (appendfile) _option_
-------------------------------

Type: string, expanded
Default: unset

This option is mutually exclusive with the "file" option. When it is
set, the string is expanded, and the message is delivered into a new
file or files in or below the given directory, instead of being
appended to a single mailbox file.  A number of different formats are
provided (see "maildir_format" and "mailstore_format"), and see section
"Operational details for delivery to a new file" for further details of
this form of delivery.


File: exim.info,  Node: directory_mode (appendfile),  Next: escape_string (appendfile),  Prev: directory (appendfile),  Up: Private options for appendfile

directory_mode (appendfile) _option_
------------------------------------

Type: octal integer
Default: 0700

If "appendfile" creates any directories as a result of the
"create_directory" option, their mode is specified by this option.


File: exim.info,  Node: escape_string (appendfile),  Next: file (appendfile),  Prev: directory_mode (appendfile),  Up: Private options for appendfile

escape_string (appendfile) _option_
-----------------------------------

Type: string
Default: ">From "

See "check_string" above.


File: exim.info,  Node: file (appendfile),  Next: file_format (appendfile),  Prev: escape_string (appendfile),  Up: Private options for appendfile

file (appendfile) _option_
--------------------------

Type: string, expanded
Default: unset

This option is mutually exclusive with the "directory" option. It need
not be set when "appendfile" is being used to deliver to files whose
names are obtained from forwarding, filtering, or aliasing address
expansions (by default under the instance name "address_file"), as in
those cases the file name is associated with the address. Otherwise,
the "file" option must be set unless the "directory" option is set.
Either "use_fcntl_lock" or "use_lockfile" (or both) must be set with
"file".  If you are using more than one host to deliver over NFS into
the same mailboxes, you should always use lock files.

The string value is expanded for each delivery, and must yield an
absolute path. The most common settings of this option are variations
on one of these examples:

     file = /var/spool/mail/$local_part
     file = /home/$local_part/inbox
     file = $home/inbox

In the first example, all deliveries are done into the same directory.
If Exim is configured to use lock files (see "use_lockfile" below) it
must be able to create a file in the directory, so the `sticky' bit
must be turned on for deliveries to be possible, or alternatively the
"group" option can be used to run the delivery under a group id which
has write access to the directory.

If there is no file name, or the expansion fails, or a local part
contains a forward slash character, a delivery error occurs.


File: exim.info,  Node: file_format (appendfile),  Next: file_must_exist (appendfile),  Prev: file (appendfile),  Up: Private options for appendfile

file_format (appendfile) _option_
---------------------------------

Type: string
Default: unset

This option requests the transport to check the format of an existing
file before adding to it. The check consists of matching a specific
string at the start of the file. A list of check strings may be given,
and associated with each is the the name of a transport. If the
transport associated with a matched string is not the current
transport, control is passed over to the other transport. There should
always be an even number of items in a "file_format" setting. For
example, if the standard "local_delivery" transport has this added to
it:

     file_format = "From       : local_delivery :\
                    \1\1\1\1\n : local_mmdf_delivery"

then mailboxes that begin with `From' are handled by this transport,
but if a mailbox begins with four binary ones followed by a newline,
control is passed to a transport called "local_mmdf_delivery" which
presumably is configured to do the delivery in MMDF format. If a
mailbox does not exist or is empty, it is assumed to match the current
transport. If the start of a mailbox doesn't match any string, or if
the transport named for a given string is not defined, delivery is
deferred.


File: exim.info,  Node: file_must_exist (appendfile),  Next: from_hack (appendfile),  Prev: file_format (appendfile),  Up: Private options for appendfile

file_must_exist (appendfile) _option_
-------------------------------------

Type: boolean
Default: false

If this option is true, the file specified by the "file" option must
exist, and an error occurs if it does not. Otherwise, it is created if
it does not exist.


File: exim.info,  Node: from_hack (appendfile),  Next: group (appendfile),  Prev: file_must_exist (appendfile),  Up: Private options for appendfile

from_hack (appendfile) _option_
-------------------------------

Type: boolean
Default: true

This option is obsolete and is retained only for backwards
compatibility. It has been replaced by "check_string" and
"escape_string". If it is explicitly unset (that is, if "no_from_hack"
is specified), it causes both the new options to be unset. Otherwise it
is ignored.


File: exim.info,  Node: group (appendfile),  Next: lock_fcntl_timeout (appendfile),  Prev: from_hack (appendfile),  Up: Private options for appendfile

group (appendfile) _option_
---------------------------

Type: string
Default: unset

If this option is set, it specifies the group under whose gid the
delivery process is to be run, and, if "check_group" is set, the group
owner of an existing file to which the message is to be appended.  If
the option is not set, a value associated with a user may be used (see
below); otherwise a value must have been associated with the address by
the director which handled it. If the string contains no $ characters,
it is resolved when Exim starts up. Otherwise, the string is expanded
at the time the transport is run, and must yield either a digit string
or a name which can be looked up using "getgrnam()".

The "group" option is commonly set for local deliveries on systems
where the set of user mailboxes is in a single directory owned by a
group such as `mail'.  Note that it should not be set on the instance
of "appendfile" that is used for deliveries to files specified by users
in their forward files (called "address_file" in the default
configuration), because such deliveries should take place under the
individual users' personal uids and gids.


File: exim.info,  Node: lock_fcntl_timeout (appendfile),  Next: lock_interval (appendfile),  Prev: group (appendfile),  Up: Private options for appendfile

lock_fcntl_timeout (appendfile) _option_
----------------------------------------

Type: time
Default: 0s

By default, the "appendfile" transport uses non-blocking calls to
"fcntl()" when locking an open mailbox file. If the call fails, it
sleeps for "lock_interval" and tries again, up to "lock_retries" times.
Non-blocking calls are used so that the file is not kept open during
the wait for the lock; the reason for this is to make it as safe as
possible for deliveries over NFS in the case when processes might be
accessing an NFS mailbox without using a lock file. This should not be
done, but misunderstandings and hence misconfigurations are not unknown.

On a busy system, however, the performance of a non-blocking lock
approach is not as good as using a blocking lock with a timeout. In
this case, the waiting is done inside the system call, and Exim's
delivery process acquires the lock and can proceed as soon as the
previous lock holder releases it.

If "lock_fcntl_timeout" is set to a non-zero time, blocking locks, with
that timeout, are used. There may still be some retrying: the maximum
number of retries is

     (lock_retries * lock_interval) / lock_fcntl_timeout

rounded up to the next whole number. In other words, the total time
during which "appendfile" is trying to get a lock is roughly the same,
unless "lock_fcntl_timeout" is set very large.

You should consider setting this option if you are getting a lot of
delayed local deliveries because of errors of the form

     failed to lock mailbox /some/file (fcntl)


File: exim.info,  Node: lock_interval (appendfile),  Next: lock_retries (appendfile),  Prev: lock_fcntl_timeout (appendfile),  Up: Private options for appendfile

lock_interval (appendfile) _option_
-----------------------------------

Type: time
Default: 3s

This specifies the time to wait between attempts to lock the file. See
below for details of locking.


File: exim.info,  Node: lock_retries (appendfile),  Next: lockfile_mode (appendfile),  Prev: lock_interval (appendfile),  Up: Private options for appendfile

lock_retries (appendfile) _option_
----------------------------------

Type: integer
Default: 10

This specifies the maximum number of attempts to lock the file. A value
of zero is treated as 1. See below for details of locking.


File: exim.info,  Node: lockfile_mode (appendfile),  Next: lockfile_timeout (appendfile),  Prev: lock_retries (appendfile),  Up: Private options for appendfile

lockfile_mode (appendfile) _option_
-----------------------------------

Type: octal integer
Default: 0600

This specifies the mode of the created lock file, when a lock file is
being used (see "use_lockfile").


File: exim.info,  Node: lockfile_timeout (appendfile),  Next: maildir_format (appendfile),  Prev: lockfile_mode (appendfile),  Up: Private options for appendfile

lockfile_timeout (appendfile) _option_
--------------------------------------

Type: time
Default: 30m

When a lock file is being used (see "use_lockfile"), if a lock file
already exists and is older than this value, it is assumed to have been
left behind by accident, and Exim attempts to remove it.


File: exim.info,  Node: maildir_format (appendfile),  Next: maildir_retries (appendfile),  Prev: lockfile_timeout (appendfile),  Up: Private options for appendfile

maildir_format (appendfile) _option_
------------------------------------

Type: boolean
Default: false

If this option is set with the "directory" option, the delivery is into
a new file in the `maildir' format that is used by some other mail
software.  The option is available only if SUPPORT_MAILDIR is present in
`Local/Makefile'.  See section "Operational details for delivery to a
new file" below for further details.


File: exim.info,  Node: maildir_retries (appendfile),  Next: maildir_tag (appendfile),  Prev: maildir_format (appendfile),  Up: Private options for appendfile

maildir_retries (appendfile) _option_
-------------------------------------

Type: integer
Default: 10

This option specifies the number of times to retry when writing a file
in `maildir' format. See section "Operational details for delivery to a
new file" below.


File: exim.info,  Node: maildir_tag (appendfile),  Next: mailstore_format (appendfile),  Prev: maildir_retries (appendfile),  Up: Private options for appendfile

maildir_tag (appendfile) _option_
---------------------------------

Type: string, expanded
Default: unset

This option applies only to deliveries in maildir format, and is
described in section "Operational details for delivery to a new file"
below.


File: exim.info,  Node: mailstore_format (appendfile),  Next: mailstore_prefix (appendfile),  Prev: maildir_tag (appendfile),  Up: Private options for appendfile

mailstore_format (appendfile) _option_
--------------------------------------

Type: boolean
Default: false

If this option is set with the "directory" option, the delivery is into
two new files in  `mailstore' format. The option is available only if
SUPPORT_MAILSTORE is present in `Local/Makefile'. See section
"Operational details for delivery to a new file" below for further
details.


File: exim.info,  Node: mailstore_prefix (appendfile),  Next: mailstore_suffix (appendfile),  Prev: mailstore_format (appendfile),  Up: Private options for appendfile

mailstore_prefix (appendfile) _option_
--------------------------------------

Type: string, expanded
Default: unset

This option applies only to deliveries in mailstore format, and is
described in section "Operational details for delivery to a new file"
below.


File: exim.info,  Node: mailstore_suffix (appendfile),  Next: mbx_format (appendfile),  Prev: mailstore_prefix (appendfile),  Up: Private options for appendfile

mailstore_suffix (appendfile) _option_
--------------------------------------

Type: string, expanded
Default: unset

This option applies only to deliveries in mailstore format, and is
described in section "Operational details for delivery to a new file"
below.


File: exim.info,  Node: mbx_format (appendfile),  Next: mode (appendfile),  Prev: mailstore_suffix (appendfile),  Up: Private options for appendfile

mbx_format (appendfile) _option_
--------------------------------

Type: boolean
Default: false

This option is available only if Exim has been compiled with SUPPORT_MBX
set in `Local/Makefile'. If "mbx_format" is set with the "file" option,
the message is appended to the mailbox file in MBX format instead of
traditional Unix format. This format is supported by Pine4 and its
associated IMAP and POP daemons, and is implemented by the "c-client"
library that they all use. The "prefix" and "suffix" options are not
automatically changed by the use of "mbx_format"; they should normally
be set empty.

If none of the locking options are mentioned in the configuration,
"use_mbx_lock" is assumed and the other locking options default to
false. It is possible to specify the other kinds of locking with
"mbx_format", but "use_fcntl_lock" and "use_mbx_lock" are mutually
exclusive. MBX locking inter~works with "c-client", providing for
shared access to the mailbox. It should not be used if any program that
does not use this form of locking is going to access the mailbox, nor
should it be used if the mailbox file is NFS mounted, because it works
only when the mailbox is accessed from a single host.

If you set "use_fcntl_lock" with an MBX-format mailbox, you cannot use
the standard version of "c-client", because as long as it has a mailbox
open (this means for the whole of a Pine or IMAP session), Exim will
not be able to append messages to it.


File: exim.info,  Node: mode (appendfile),  Next: mode_fail_narrower (appendfile),  Prev: mbx_format (appendfile),  Up: Private options for appendfile

mode (appendfile) _option_
--------------------------

Type: octal integer
Default: 0600

If the output file is created, it is given this mode. If it already
exists and has wider permissions, they are reduced to this mode. If it
has narrower permissions, an error occurs unless "mode_fail_narrower"
is false. However, if the delivery is the result of a "save" command in
a filter file specifing a particular mode, the mode of the output file
is always forced to take that value, and this option is ignored.


File: exim.info,  Node: mode_fail_narrower (appendfile),  Next: notify_comsat (appendfile),  Prev: mode (appendfile),  Up: Private options for appendfile

mode_fail_narrower (appendfile) _option_
----------------------------------------

Type: boolean
Default: true

This option applies in the case when an existing mailbox file has a
narrower mode than that specified by the "mode" option. If
"mode_fail_narrower" is true, the delivery is frozen (`mailbox has the
wrong mode'); otherwise Exim continues with the delivery attempt, using
the existing mode of the file.


File: exim.info,  Node: notify_comsat (appendfile),  Next: prefix (appendfile),  Prev: mode_fail_narrower (appendfile),  Up: Private options for appendfile

notify_comsat (appendfile) _option_
-----------------------------------

Type: boolean
Default: false

If this option is true, the "comsat" daemon is notified after every
successful delivery to a user mailbox. This is the daemon that notifies
logged on users about incoming mail.


File: exim.info,  Node: prefix (appendfile),  Next: quota (appendfile),  Prev: notify_comsat (appendfile),  Up: Private options for appendfile

prefix (appendfile) _option_
----------------------------

Type: string, expanded
Default: see below

The string specified here is expanded and output at the start of every
message.  The default is

     prefix = "From ${if def:return_path{$return_path}{MAILER-DAEMON}}\
       ${tod_bsdinbox}\n"

This line can be suppressed by setting

     prefix =

and this is usually necessary when doing batch SMTP deliveries, or
delivering into individual files or MBX-format mailboxes.


File: exim.info,  Node: quota (appendfile),  Next: quota_filecount (appendfile),  Prev: prefix (appendfile),  Up: Private options for appendfile

quota (appendfile) _option_
---------------------------

Type: string, expanded
Default: unset

This option imposes a limit on the size of the file to which Exim is
appending, or to the total space used in the directory tree if the
"directory" option is set. In the latter case, computation of the space
used is expensive, as all the files in the directory (and any
sub-directories) have to be individually inspected and their sizes
summed (but see "quota_size_regex" below). Also, there is no interlock
against two simultaneous deliveries into a multi-file mailbox. For
single-file mailboxes, of course, an interlock is a necessity.

A file's size is take as its "used" value. Because of blocking effects,
this may be a lot less than the actual amount of disc space allocated
to the file.  If the sizes of a number of files are being added up, the
rounding effect can become quite noticeable, especially on systems that
have large block sizes.  Nevertheless, it seems best to stick to the
"used" figure, because this is the obvious value which users will
understand most easily.

The value of the option is expanded, and must then be a numerical value
(decimal point allowed), optionally followed by one of the letters K or
M. The expansion happens while Exim is running as root or the Exim
user, before "setuid()" is called for the delivery, so files that are
inaccessible to the end user can be used to hold quota values that are
looked up in the expansion.  When delivery fails because this quota is
exceeded, the handling of the error is as for system quota failures.

By default, Exim's quota checking mimics system quotas, and restricts
the mailbox to the specified maximum size, though the value is not
accurate to the last byte, owing to separator lines and additional
headers that may get added during message delivery. When a mailbox is
nearly full, large messages may get refused even though small ones are
accepted, because the size of the current message is added to the quota
when the check is made. This behaviour can be changed by setting
"quota_is_inclusive" false. When this is done, the check for exceeding
the quota does not include the current message. Thus, deliveries
continue until the quota has been exceeded; thereafter, no further
messages are delivered.  See also "quota_warn_threshold".


File: exim.info,  Node: quota_filecount (appendfile),  Next: quota_is_inclusive (appendfile),  Prev: quota (appendfile),  Up: Private options for appendfile

quota_filecount (appendfile) _option_
-------------------------------------

Type: integer
Default: 0

This option applies when the "directory" option is set. It limits the
total number of files in the directory (compare the inode limit in
system quotas). It can only be used if "quota" is also set.


File: exim.info,  Node: quota_is_inclusive (appendfile),  Next: quota_size_regex (appendfile),  Prev: quota_filecount (appendfile),  Up: Private options for appendfile

quota_is_inclusive (appendfile) _option_
----------------------------------------

Type: boolean
Default: true

See "quota" above.


File: exim.info,  Node: quota_size_regex (appendfile),  Next: quota_warn_message (appendfile),  Prev: quota_is_inclusive (appendfile),  Up: Private options for appendfile

quota_size_regex (appendfile) _option_
--------------------------------------

Type: string
Default: unset

This option applies when one of the delivery modes that writes a
separate file for each message is being used. When Exim wants to find
the size of one of these files in order to test the quota, it first
checks "quota_size_regex".  If this is set to a regular expression that
matches the file name, and it captures one string, that string is
interpreted as a representation of the file's size. This feature is
useful only when users have no shell access to their mailboxes -
otherwise they could defeat the quota simply by renaming the files.
This facility can be used with maildir deliveries, by setting
"maildir_tag" to add the file length to the file name. For example:

     maildir_tag = ,S=$message_size
     quota_size_regex = S=(\d+)$

The string is not expanded.


File: exim.info,  Node: quota_warn_message (appendfile),  Next: quota_warn_threshold (appendfile),  Prev: quota_size_regex (appendfile),  Up: Private options for appendfile

quota_warn_message (appendfile) _option_
----------------------------------------

Type: string, expanded
Default: see below

See below for the use of this option. If it is not set when
"quota_warn_threshold" is set, it defaults to

     quota_warn_message = "\
       To: $local_part@$domain\n\
       Subject: Your mailbox\n\n\
       This message is automatically created \
       by mail delivery software.\n\n\
       The size of your mailbox has exceeded \
       a warning threshold that is\n\
       set by the system administrator.\n"


File: exim.info,  Node: quota_warn_threshold (appendfile),  Next: require_lockfile (appendfile),  Prev: quota_warn_message (appendfile),  Up: Private options for appendfile

quota_warn_threshold (appendfile) _option_
------------------------------------------

Type: string, expanded
Default: "0"

This option is expanded in the same way as "quota" (see above). If the
resulting value is greater than zero, and delivery of the message
causes the size of the file or total space in the directory tree to
cross the given threshold, a warning message is sent. If "quota" is
also set, the threshold may be specified as a percentage of it by
following the value with a percent sign.  For example:

     quota = 10M
     quota_warn_threshold = 75%

If "quota" is not set, a setting of "quota_warn_threshold" that ends
with a percent sign is ignored.

The warning message itself is specified by the "quota_warn_message"
option, and it must start with a "To:" header line containing the
recipient(s). A "Subject:" line should also normally be supplied. The
"quota" option does not have to be set in order to use this option;
they are independent of one another except when the threshold is
specified as a percentage.


File: exim.info,  Node: require_lockfile (appendfile),  Next: retry_use_local_part (appendfile),  Prev: quota_warn_threshold (appendfile),  Up: Private options for appendfile

require_lockfile (appendfile) _option_
--------------------------------------

Type: boolean
Default: true

When a lock file is being used (see "use_lockfile") and
"require_lockfile" is true, a lock file must be created before delivery
can proceed. If the option is not true, failure to create a lock file
because of a `permission denied' error is not treated as an error,
though failure of the "fcntl()" locking function is. This option should
always be set when delivering from more than one host over NFS.  It is
required to be set if the "file" option is set and "use_fcntl_lock" is
not set, except when "mbx_format" is set.


File: exim.info,  Node: retry_use_local_part (appendfile),  Next: suffix (appendfile),  Prev: require_lockfile (appendfile),  Up: Private options for appendfile

retry_use_local_part (appendfile) _option_
------------------------------------------

Type: boolean
Default: true

When a local delivery suffers a temporary failure, both the local part
and the domain are normally used to form a key that is used to
determine when next to try the address. This handles common cases such
as exceeding a quota, where the failure applies to the specific local
part. However, when local delivery is being used to collect messages
for onward transmission by some other means, a temporary failure may
not depend on the local part at all. Setting this option false causes
Exim to use only the domain when handling retries for this transport.


File: exim.info,  Node: suffix (appendfile),  Next: use_crlf (appendfile),  Prev: retry_use_local_part (appendfile),  Up: Private options for appendfile

suffix (appendfile) _option_
----------------------------

Type: string, expanded
Default: "\n"

The string specified here is expanded and output at the end of every
message.  The default blank line can be suppressed by setting

     suffix =

and this is usually necessary when doing batch SMTP deliveries, or
delivering into individual files or MBX-format mailboxes.


File: exim.info,  Node: use_crlf (appendfile),  Next: use_fcntl_lock (appendfile),  Prev: suffix (appendfile),  Up: Private options for appendfile

use_crlf (appendfile) _option_
------------------------------

Type: boolean
Default: false

This option causes lines to be terminated with the two-character CRLF
sequence (carriage return, linefeed) instead of just a linefeed
character. In the case of batched SMTP, the byte sequence written to
the file is then an exact image of what would be sent down a real SMTP
connection.

The contents of the "prefix" and "suffix" options are written verbatim,
so must contain their own carriage return characters if these are
needed. Since the default values for both "prefix" and "suffix" end
with a single linefeed, their values almost always need to be changed
if "use_crlf" is set.


File: exim.info,  Node: use_fcntl_lock (appendfile),  Next: use_lockfile (appendfile),  Prev: use_crlf (appendfile),  Up: Private options for appendfile

use_fcntl_lock (appendfile) _option_
------------------------------------

Type: boolean
Default: see below

This option controls the use of the "fcntl()" function to lock a file
for exclusive use when a message is being appended. It is set by
default unless "use_mbx_lock" is set. Otherwise, it should be turned
off only if you know that all your MUAs use lock file locking. When
"use_fcntl_lock" is off, "use_lockfile" and "require_lockfile" must
both be on if "mbx_format" is not set.


File: exim.info,  Node: use_lockfile (appendfile),  Next: use_mbx_lock (appendfile),  Prev: use_fcntl_lock (appendfile),  Up: Private options for appendfile

use_lockfile (appendfile) _option_
----------------------------------

Type: boolean
Default: see below

If this option is turned off, Exim does not attempt to create a lock
file when appending to a file. Thus the only locking is by "fcntl()".
This option is set by default unless "use_mbx_lock" is set. It is not
possible to turn both "use_lockfile" and "use_fcntl_lock" off, except
when "mbx_format" is set.  You should only turn "use_lockfile" off if
you are absolutely sure that every MUA that is ever going to look at
your users' mailboxes uses "fcntl()" rather than a lock file, and even
then only when you are not delivering over NFS from more than one host.
In order to append to an NFS file safely from more than one host, it is
necessary to take out a lock before opening the file, and the lock file
achieves this. Otherwise, even with "fcntl()" locking, there is a risk
of file corruption. See also the "require_lockfile" option.


File: exim.info,  Node: use_mbx_lock (appendfile),  Next: user (appendfile),  Prev: use_lockfile (appendfile),  Up: Private options for appendfile

use_mbx_lock (appendfile) _option_
----------------------------------

Type: boolean
Default: see below

This option is available only if Exim has been compiled with SUPPORT_MBX
set in `Local/Makefile'. Setting the option specifies that special MBX
locking rules be used. It is set by default if "mbx_format" is set and
none of the locking options are mentioned in the configuration. The
locking rules are the same as are used by the "c-client" library that
underlies Pine4 and the IMAP4 and POP daemons that come with it (see
the discussion below). The rules allow for shared access to the
mailbox. However, this kind of locking does not work when the mailbox
is NFS mounted.


File: exim.info,  Node: user (appendfile),  Prev: use_mbx_lock (appendfile),  Up: Private options for appendfile

user (appendfile) _option_
--------------------------

Type: string
Default: unset

If this option is set, it specifies the user under whose uid the
delivery process is to be run, and which must be the owner of an
existing file to which the message is appended.  If the option is not
set, a value must have been associated with the address by the director
that handled it. If the string contains no $ characters, it is resolved
when Exim starts up. Otherwise, the string is expanded at the time the
transport is run, and must yield either a digit string or a name which
can be looked up using "getpwnam()". When "getpwnam()" is used, either
at start-up time or later, the group id value associated with the user
is taken as the value to be used if the "group" option is not set.


File: exim.info,  Node: Operational details for appending,  Next: Operational details for delivery to a new file,  Prev: Private options for appendfile,  Up: The appendfile transport

Operational details for appending
=================================

Before appending to a file, Exim proceeds as follows:

   * If the name of the file is "/dev/null", no action is taken, and a
     success return is given.

   * If any directories on the file's path are missing, Exim creates
     them if the "create_directory" option is set. A created
     directory's mode is given by the "directory_mode" option.

   * If "file_format" is set, the format of an existing file is
     checked. If this indicates that a different transport should be
     used, control is passed to that transport.

   * If "use_lockfile" is set, a lock file is built in a way that will
     work reliably over NFS, as follows:

        * Create a `hitching post' file whose name is that of the lock
          file with the current time, primary host name, and process id
          added, by opening for writing as a new file. If this fails
          with an access error, the message is frozen unless
          "require_lockfile" is false. Otherwise delivery is deferred.

        * Close the hitching post file, and hard link it to the lock
          file name.

        * If the call to "link()" succeeds, creation of the lock file
          has succeeded.  Unlink the hitching post name.

        * Otherwise, use "stat()" to get information about the hitching
          post file, and then unlink hitching post name. If the number
          of links is exactly two, creation of the lock file succeeded
          but something (for example, an NFS server crash and restart)
          caused this fact not to be communicated to the "link()" call.

        * If creation of the lock file failed, wait for "lock_interval"
          and try again, up to "lock_retries" times. However, since any
          program that writes to a mailbox should complete its task
          very quickly, it is reasonable to time out old lock files
          that are normally the result of user agent and system
          crashes. If an existing lock file is older than
          "lockfile_timeout" Exim attempts to unlink it before trying
          again.

   * A call is made to "lstat()" to discover whether the main file
     exists, and if so, what its characteristics are. If "lstat()"
     fails for any reason other than non-existence, delivery is
     deferred.

   * If the file does exist and is a symbolic link, delivery is
     deferred and the message is frozen, unless the "allow_symlinks"
     option is set, in which case the ownership of the link is checked,
     and then "stat()" is called to find out about the real file, which
     is then subjected to the checks below. The check on the top-level
     link ownership prevents one user creating a link for another's
     mailbox in a sticky directory, though allowing symbolic links in
     this case is definitely not a good idea. If there is a chain of
     symbolic links, the intermediate ones are not checked.

   * If the file already exists but is not a regular file, or if the
     file's owner and group (if the group is being checked - see
     "check_group" above) are different from the user and group under
     which the delivery is running, delivery is deferred, and the
     message is frozen.

   * If the file's permissions are more generous than specified, they
     are reduced.  If they are insufficient, delivery is deferred, and
     the message is frozen, unless "mode_fail_narrower" is set false,
     in which case the delivery is tried using the existing permissions.

   * The file's inode number is saved, and it is then opened for
     appending. If this fails because the file has vanished,
     "appendfile" behaves as if it hadn't existed (see below). If the
     open failure is EWOULDBLOCK, just defer delivery; otherwise defer
     and freeze the message.

   * If the file is opened successfully, check that the inode number
     hasn't changed, that it is still a regular file, and that the
     owner and permissions have not changed. If anything is wrong,
     defer and freeze the message.

   * If the file did not exist originally, defer delivery and freeze
     the message if the "file_must_exist" option is set. Otherwise,
     check that the file is being created in a permitted directory if
     the "create_file" option is set (deferring and freezing on
     failure), and then open for writing as a new file, with the O_EXCL
     and O_CREAT options, except when dealing with a symbolic link (the
     "allow_symlinks" option must be set). In this case, which can
     happen if the link points to a non-existent file, the file is
     opened for writing using O_CREAT but not O_EXCL, because that
     prevents link following.

   * If opening fails because the file exists, obey the tests given
     above for existing files. However, to avoid looping in a situation
     where the file is being continuously created and destroyed, the
     exists/not-exists loop is broken after 10 repetitions, and the
     message is then frozen.

   * If opening fails with any other error, defer delivery.

   * Once the file is open, unless both "use_fcntl_lock" and
     "use_mbx_lock" are false, it is locked using "fcntl()". In the
     former case, an exclusive lock is requested, while in the latter,
     Exim takes out a shared lock on the open file, and an exclusive
     lock on the file whose name is

          /tmp/.<device-number>.<inode-number>

     using the device and inode numbers of the open mailbox file, in
     accordance with the MBX locking rules.

     If "fcntl()" locking fails, there are two possible courses of
     action, depending on the value of "lock_fcntl_timeout". If its
     value is zero, the file is closed, Exim waits for "lock_interval"
     and then goes back and re-opens it as above and tries to lock it
     again. This happens up to "lock_retries" times, after which the
     delivery is deferred.

     If "lock_fcntl_timeout" has a value greater than zero, a blocking
     call to "fcntl()" with that timeout is used, so there has already
     been some waiting involved. Nevertheless, Exim does not give up
     immediately. It retries up to

          (lock_retries * lock_interval) / lock_fcntl_timeout

     times (rounded up).

At the end of delivery, Exim closes the file (which releases the
"fcntl()" lock) and then deletes the lock file if one was created.


File: exim.info,  Node: Operational details for delivery to a new file,  Prev: Operational details for appending,  Up: The appendfile transport

Operational details for delivery to a new file
==============================================

When the "directory" option is set, each message is delivered into a
newly-created file or set of files. No locking is required while
writing the message, so the various locking options of the transport
are ignored. The `From' line that by default separates messages in a
single file is not normally needed, nor is the escaping of message
lines that start with `From', and there is no need to ensure a newline
at the end of each message. Consequently, the default settings in
"appendfile" need changing as follows:

       check_string = ""
       prefix = ""
       suffix = ""

There are three different ways in which delivery to individual files
can be done, depending on the settings of the "maildir_format" and
"mailstore_format" options. Note that code to support maildir and
mailstore formats is not included in the binary unless SUPPORT_MAILDIR
or SUPPORT_MAILSTORE, respectively, are set in `Local/Makefile'.

In all three cases an attempt is made to create the directory and any
necessary sub-directories if they do not exist, provided that the
"create_directory" option is set (the default). A created directory's
mode is given by the "directory_mode" option. If creation fails, or if
the "create_directory" option is not set when creation is required, the
delivery is deferred.

   * If neither "maildir_format" nor "mailstore_format" is set, a
     single new file is created directly in the named directory. For
     example, when delivering messages into files using the "bsmtp"
     option (see section "Outgoing batched SMTP" in chapter "SMTP
     processing"), a setting such as

          directory = /var/bsmtp/${host}

     might be used. A message is written to a file with a temporary
     name, which is then renamed when the delivery is complete. The
     final name is constructed from the time and the file's inode
     number, and starts with the letter `q' for compatibility with
     "smail".

   * If the "maildir_format" option is true, Exim delivers each message
     by writing it to a file whose name is "tmp/<time>.<pid>.<host>" in
     the given directory, and then renaming it into the "new"
     sub-directory if all goes well.

     Before opening the temporary file, Exim calls "stat()" on its
     name. If any response other than ENOENT (does not exist) is given,
     it waits 2 seconds and tries again, up to "maildir_retries" times.

     If Exim is required to check a "quota" setting before a maildir
     delivery, it looks for a file called "maildirfolder" in the
     maildir directory (alongside "new", "cur", "tmp"). If this exists,
     it assumes the directory is a maildir++ folder directory, which is
     one level down from the user's toplevel mailbox directory. This
     causes it to start at the parent directory instead of the current
     directory when calculating the amount of space used.

     If "maildir_tag" is set, the string is expanded for each delivery.
     This is done after the message has been written, so that the value
     of the $message_size variable can be set accurately during the
     expansion. If the expansion is forced to fail, the tag is ignored,
     but a non-forced failure causes delivery to be deferred. The
     expanded tag may contain any printing characters except `/'. Any
     other characters in the string are ignored; if the resulting
     string is empty, it is ignored. If it starts with an alphanumeric
     character, a leading colon is inserted.

     When the temporary maildir file is renamed into the "new"
     sub-directory, the tag is added to its name. However, if adding
     the tag takes the length of the name to the point where the test
     "stat()" call fails with ENAMETOOLONG, the tag is dropped and the
     maildir file is created with no tag. Tags can be used to encode
     the size of files in their names; see "quota_size_regex" above for
     an example.

   * If the "mailstore_format" option is true, each message is written
     as two files in the given directory. A unique base name is
     constructed from the message id and the current delivery process,
     and the files that are written use this base name plus the
     suffixes ".env" and ".msg". The ".env" file contains the message's
     envelope, and the ".msg" file contains the message itself.

     During delivery, the envelope is first written to a file with the
     suffix ".tmp". The ".msg" file is then written, and when it is
     complete, the ".tmp" file is renamed as the ".env" file. Programs
     that access messages in mailstore format should wait for the
     presence of both a ".msg" and a ".env" file before accessing
     either of them. An alternative approach is to wait for the absence
     of a ".tmp" file.

     The envelope file starts with any text defined by the
     "mailstore_prefix" option, expanded and terminated by a newline if
     there isn't one. Then follows the sender address on one line, then
     all the recipient addresses, one per line.  There can be more than
     one recipient only if the "batch" option is set.  Finally,
     "mailstore_suffix" is expanded and the result appended to the file,
     followed by a newline if it does not end with one.

     If expansion of the prefix or suffix ends with a forced failure,
     it is ignored. Other expansion errors are treated as serious
     configuration errors, and delivery is deferred.


File: exim.info,  Node: The autoreply transport,  Next: The lmtp transport,  Prev: The appendfile transport,  Up: Top

The autoreply transport
***********************

The "autoreply" transport is not a true transport in that it does not
cause the message to be transmitted. Instead, it generates another mail
message. It is usually run as the result of mail filtering. A
`vacation' message is the standard example.

"Autoreply" is implemented as a local transport so that it runs under
the uid and gid of the local user and with appropriate current and home
directories (see chapter "Environment for running local transports").
The parameters of the message to be sent can be specified in the
configuration by the options described below, but in the common case
when "autoreply" is activated as a result of filtering, none of them
are normally set, because all the information is obtained from the
filter file.

In an attempt to reduce the possibility of message cascades, messages
created by the "autoreply" transport always take the form of delivery
error messages.  That is, the envelope sender field is empty.

There is a subtle difference between directing a message to a pipe
transport that generates some text to be returned to the sender, and
directing it to an autoreply transport. This difference is noticeable
only if more than one address from the same message is so handled. In
the case of a pipe, the separate outputs from the different addresses
are gathered up and returned to the sender in a single message, while
if "autoreply" is used, a separate message is generated for each
address passed to it.

The private options of the "autoreply" transport that describe the
message are used only when the address passed to it does not contain
any reply information.  Thus the message is specified entirely by the
director or by the transport; it is never built from a mixture of
options. The remaining private options ("file_optional", "group",
"initgroups", "mode", "return_message", and "user") apply in all cases.

Non-printing characters are not permitted in the header lines generated
for the message that "autoreply" creates, with the exception of space
and tab. Other non-printing characters are converted into escape
sequences. Whether characters with the top bit set count as printing
characters or not is controlled by the "print_topbitchars" global
option.

If any of the generic options for manipulating headers (for example,
"headers_add") are set on an "autoreply" transport, they apply to the
copy of the original message that is included in the generated message
when "return_message" is set. They do not apply to the generated
message itself.

If the "autoreply" transport receives return code 2 from Exim when it
submits the message, indicating that there were no recipients, it does
not treat this as an error. This means that autoreplies sent to
$sender_address when this is empty (because the incoming message is a
delivery failure report) do not cause problems.



* Menu:

* Private options for autoreply::


File: exim.info,  Node: Private options for autoreply,  Prev: The autoreply transport,  Up: The autoreply transport

Private options for autoreply
=============================



* Menu:

* bcc (autoreply)::
* cc (autoreply)::
* file (autoreply)::
* file_expand (autoreply)::
* file_optional (autoreply)::
* from (autoreply)::
* group (autoreply)::
* headers (autoreply)::
* initgroups (autoreply)::
* log (autoreply)::
* mode (autoreply)::
* once (autoreply)::
* once_file_size (autoreply)::
* once_repeat (autoreply)::
* reply_to (autoreply)::
* return_message (autoreply)::
* subject (autoreply)::
* text (autoreply)::
* to (autoreply)::
* user (autoreply)::


File: exim.info,  Node: bcc (autoreply),  Next: cc (autoreply),  Prev: Private options for autoreply,  Up: Private options for autoreply

bcc (autoreply) _option_
------------------------

Type: string, expanded
Default: unset

Specifies the addresses that are to receive `blind carbon copies' of the
message when the message is specified by the transport. The string is
expanded.


File: exim.info,  Node: cc (autoreply),  Next: file (autoreply),  Prev: bcc (autoreply),  Up: Private options for autoreply

cc (autoreply) _option_
-----------------------

Type: string, expanded
Default: unset

Specifies recipients of the message and the contents of the "Cc:"
header when the message is specified by the transport. The string is
expanded.


File: exim.info,  Node: file (autoreply),  Next: file_expand (autoreply),  Prev: cc (autoreply),  Up: Private options for autoreply

file (autoreply) _option_
-------------------------

Type: string, expanded
Default: unset

The contents of the file are sent as the body of the message when the
message is specified by the transport. The string is expanded. If both
"file" and "text" are set, the text string comes first.


File: exim.info,  Node: file_expand (autoreply),  Next: file_optional (autoreply),  Prev: file (autoreply),  Up: Private options for autoreply

file_expand (autoreply) _option_
--------------------------------

Type: boolean
Default: false

If this is set, the contents of the file named by the "file" option are
subjected to string expansion as they are added to the message.


File: exim.info,  Node: file_optional (autoreply),  Next: from (autoreply),  Prev: file_expand (autoreply),  Up: Private options for autoreply

file_optional (autoreply) _option_
----------------------------------

Type: boolean
Default: false

If this option is true, no error is generated if the file named by the
"file" option does not exist or cannot be read.


File: exim.info,  Node: from (autoreply),  Next: group (autoreply),  Prev: file_optional (autoreply),  Up: Private options for autoreply

from (autoreply) _option_
-------------------------

Type: string, expanded
Default: unset

The contents of the "From:" header when the message is specified by the
transport. The string is expanded.


File: exim.info,  Node: group (autoreply),  Next: headers (autoreply),  Prev: from (autoreply),  Up: Private options for autoreply

group (autoreply) _option_
--------------------------

Type: string
Default: unset

If this option is set, it specifies the group under whose gid the
delivery process is to be run. If it is not set, a value associated
with a user may be used (see below); otherwise a value must have been
associated with the address by the director which handled it. If the
string contains no $ characters, it is resolved when Exim starts up.
Otherwise, the string is expanded at the time the transport is run, and
must yield either a digit string or a name which can be looked up using
"getgrnam()".


File: exim.info,  Node: headers (autoreply),  Next: initgroups (autoreply),  Prev: group (autoreply),  Up: Private options for autoreply

headers (autoreply) _option_
----------------------------

Type: string, expanded
Default: unset

Specified additional RFC 822 headers that are to be added to the
message when the message is specified by the transport. The string is
expanded. Several can be given by using `\n' to separate them. There is
no check on the format.


File: exim.info,  Node: initgroups (autoreply),  Next: log (autoreply),  Prev: headers (autoreply),  Up: Private options for autoreply

initgroups (autoreply) _option_
-------------------------------

Type: boolean
Default: false

If this option is true and the uid is provided by the transport, the
"initgroups()" function is called when running the transport to ensure
that any additional groups associated with the uid are set up. By
default no additional groups are present.


File: exim.info,  Node: log (autoreply),  Next: mode (autoreply),  Prev: initgroups (autoreply),  Up: Private options for autoreply

log (autoreply) _option_
------------------------

Type: string, expanded
Default: unset

This option names a file in which a record of every message sent is
logged when the message is specified by the transport (as opposed to
the director). The string is expanded.


File: exim.info,  Node: mode (autoreply),  Next: once (autoreply),  Prev: log (autoreply),  Up: Private options for autoreply

mode (autoreply) _option_
-------------------------

Type: octal integer
Default: 0600

If either the log file or the `once' file has to be created, this mode
is used.


File: exim.info,  Node: once (autoreply),  Next: once_file_size (autoreply),  Prev: mode (autoreply),  Up: Private options for autoreply

once (autoreply) _option_
-------------------------

Type: string, expanded
Default: unset

This option names a file or DBM database in which a record of each
recipient is kept when the message is specified by the transport. The
string is expanded. If "once_file_size" is not set, a DBM database is
used, and it is allowed to grow as large as necessary. If a potential
recipient is already in the database, no message is sent by default.
However, if "once_repeat" specifies a time greater than zero, the
message is sent if that much time has elapsed since a message was last
sent to this recipient. If "once" is unset, the message is always sent.

If "once_file_size" is set greater than zero, it changes the way Exim
implements the "once" option. Instead of using a DBM file to record
every recipient it sends to, it uses a regular file, whose size will
never get larger than the given value. In the file, it keeps a linear
list of recipient addresses and times at which they were sent messages.
If the file is full when a new address needs to be added, the oldest
address is dropped. If "once_repeat" is not set, this means that a
given recipient may receive multiple messages, but at unpredictable
intervals that depend on the rate of turnover of addresses in the file.
If "once_repeat" is set, it specifies a maximum time between repeats.


File: exim.info,  Node: once_file_size (autoreply),  Next: once_repeat (autoreply),  Prev: once (autoreply),  Up: Private options for autoreply

once_file_size (autoreply) _option_
-----------------------------------

Type: integer
Default: 0

See "once" above.


File: exim.info,  Node: once_repeat (autoreply),  Next: reply_to (autoreply),  Prev: once_file_size (autoreply),  Up: Private options for autoreply

once_repeat (autoreply) _option_
--------------------------------

Type: time
Default: 0s

See "once" above.


File: exim.info,  Node: reply_to (autoreply),  Next: return_message (autoreply),  Prev: once_repeat (autoreply),  Up: Private options for autoreply

reply_to (autoreply) _option_
-----------------------------

Type: string, expanded
Default: unset

Specifies the contents of the "Reply-To:" header when the message is
specified by the transport. The string is expanded.


File: exim.info,  Node: return_message (autoreply),  Next: subject (autoreply),  Prev: reply_to (autoreply),  Up: Private options for autoreply

return_message (autoreply) _option_
-----------------------------------

Type: boolean
Default: false

If this is set, a copy of the original message is returned with the new
message, subject to the maximum size set in the "return_size_limit"
general configuration option.


File: exim.info,  Node: subject (autoreply),  Next: text (autoreply),  Prev: return_message (autoreply),  Up: Private options for autoreply

subject (autoreply) _option_
----------------------------

Type: string, expanded
Default: unset

The contents of the "Subject:" header when the message is specified by
the transport. The string is expanded.


File: exim.info,  Node: text (autoreply),  Next: to (autoreply),  Prev: subject (autoreply),  Up: Private options for autoreply

text (autoreply) _option_
-------------------------

Type: string, expanded
Default: unset

This specifies a single string to be used as the body of the message
when the message is specified by the transport. The string is expanded.
If both "text" and "file" are set, the text comes first.


File: exim.info,  Node: to (autoreply),  Next: user (autoreply),  Prev: text (autoreply),  Up: Private options for autoreply

to (autoreply) _option_
-----------------------

Type: string, expanded
Default: unset

Specifies recipients of the message and the contents of the "To:"
header when the message is specified by the transport. The string is
expanded.


File: exim.info,  Node: user (autoreply),  Prev: to (autoreply),  Up: Private options for autoreply

user (autoreply) _option_
-------------------------

Type: string
Default: unset

If this option is set, it specifies the user under whose uid the
delivery process is to be run. If it is not set, a value must have been
associated with the address by the director that handled it. If the
string contains no $ characters, it is resolved when Exim starts up.
Otherwise, the string is expanded at the time the transport is run, and
must yield either a digit string or a name which can be looked up using
"getpwnam()". When "getpwnam()" is used, either at start-up time or
later, the group id value associated with the user is taken as the
value to be used if the "group" option is not set.


File: exim.info,  Node: The lmtp transport,  Next: The pipe transport,  Prev: The autoreply transport,  Up: Top

The lmtp transport
******************

The "lmtp" transport runs the LMTP protocol (RFC 2033) over a pipe to a
specified command. It is something of a cross between "pipe" and
"smtp". Exim also has support for using LMTP over TCP/IP; this is
implemented as an option for the "smtp" transport. Because LMTP is
expected to be of minority interest, the default built-time configure
in `src/EDITME' has it commented out. You need to ensure that

     TRANSPORT_LMTP=yes

is present in your "Local/Makefile" in order to have the "lmtp"
transport included in the Exim binary.

The private options of the "lmtp" transport are as follows:



* Menu:

* batch (lmtp)::
* batch_max (lmtp)::
* command (lmtp)::
* group (lmtp)::
* initgroups (lmtp)::
* retry_use_local_part (lmtp)::
* timeout (lmtp)::
* user (lmtp)::
* The lmtp transport (continued)::


File: exim.info,  Node: batch (lmtp),  Next: batch_max (lmtp),  Prev: The lmtp transport,  Up: The lmtp transport

batch (lmtp) _option_
---------------------

Type: string
Default: "none"

As for other local transports, by default each address that is directed
or routed to an "lmtp" transport is handled separately. However, the
whole point of "lmtp" is to be able to pass a single copy of a message
with more than one recipient, so "batch" should normally be set to
something other than the default.

If it is set to the string `domain', all addresses with the same domain
that are directed or routed to the transport are handled in a single
delivery. If it is set to `all', multiple domains are batched. The list
of addresses is included in the "Envelope-to:" header if
"envelope_to_add" is set. When more than one address is being delivered,
$local_part is not set, and $domain is set only if they all have the
same domain.


File: exim.info,  Node: batch_max (lmtp),  Next: command (lmtp),  Prev: batch (lmtp),  Up: The lmtp transport

batch_max (lmtp) _option_
-------------------------

Type: integer
Default: 100

This limits the number of addresses that can be handled in a batch.


File: exim.info,  Node: command (lmtp),  Next: group (lmtp),  Prev: batch_max (lmtp),  Up: The lmtp transport

command (lmtp) _option_
-----------------------

Type: string
Default: unset

This is a mandatory option, which must be set. The string is a command
which is run in a separate process. It is split up into a command name
and list of arguments, each of which is separately expanded (so
expansion cannot change the number of arguments). The command is run
directly, not via a shell. The message is passed to the new process
using the standard input and output to operate the LMTP protocol.


File: exim.info,  Node: group (lmtp),  Next: initgroups (lmtp),  Prev: command (lmtp),  Up: The lmtp transport

group (lmtp) _option_
---------------------

Type: string
Default: unset

If this option is set, it specifies the group under whose gid the
delivery process is to be run. If it is not set, a value associated
with a user may be used (see below); otherwise a value must have been
associated with the address by the director which handled it. If the
string contains no $ characters, it is resolved when Exim starts up.
Otherwise, the string is expanded at the time the transport is run, and
must yield either a digit string or a name which can be looked up using
"getgrnam()".


File: exim.info,  Node: initgroups (lmtp),  Next: retry_use_local_part (lmtp),  Prev: group (lmtp),  Up: The lmtp transport

initgroups (lmtp) _option_
--------------------------

Type: boolean
Default: false

If this option is true and the uid is provided by the transport, the
"initgroups()" function is called when running the transport to ensure
that any additional groups associated with the uid are set up. By
default no additional groups are present.


File: exim.info,  Node: retry_use_local_part (lmtp),  Next: timeout (lmtp),  Prev: initgroups (lmtp),  Up: The lmtp transport

retry_use_local_part (lmtp) _option_
------------------------------------

Type: boolean
Default: true

When a local delivery suffers a temporary failure, both the local part
and the domain are normally used to form a key that is used to
determine when next to try the address. This handles common cases such
as exceeding a quota, where the failure applies to the specific local
part. However, when local delivery is being used to collect messages
for onward transmission by some other means, a temporary failure may
not depend on the local part at all. Setting this option false causes
Exim to use only the domain when handling retries for this transport.


File: exim.info,  Node: timeout (lmtp),  Next: user (lmtp),  Prev: retry_use_local_part (lmtp),  Up: The lmtp transport

timeout (lmtp) _option_
-----------------------

Type: time
Default: 5m

The transport is aborted if the created process does not respond to LMTP
commands or message input within this timeout.


File: exim.info,  Node: user (lmtp),  Next: The lmtp transport (continued),  Prev: timeout (lmtp),  Up: The lmtp transport

user (lmtp) _option_
--------------------

Type: string
Default: unset

If this option is set, it specifies the user under whose uid the
delivery process is to be run. If it is not set, a value must have been
associated with the address by the director that handled it. If the
string contains no $ characters, it is resolved when Exim starts up.
Otherwise, the string is expanded at the time the transport is run, and
must yield either a digit string or a name which can be looked up using
"getpwnam()". When "getpwnam()" is used, either at start-up time or
later, the group id value associated with the user is taken as the
value to be used if the "group" option is not set.


File: exim.info,  Node: The lmtp transport (continued),  Prev: user (lmtp),  Up: The lmtp transport

Here is an example of a typical LMTP transport:

     lmtp:
       driver = lmtp
       command = /some/local/lmtp/delivery/program
       batch = all
       batch_max = 20
       user = exim

This delivers up to 20 addresses at a time, in a mixture of domains if
necessary, running as the user "exim".


File: exim.info,  Node: The pipe transport,  Next: The smtp transport,  Prev: The lmtp transport,  Up: Top

The pipe transport
******************

The "pipe" transport is used to deliver messages via a pipe to a command
running in another process. This can happen when when a director
explicitly directs a message to a "pipe" transport, and also when an
address is expanded via an alias, filter, or forward file that
specifies a pipe command. In this case, $local_part contains the local
part that was aliased or forwarded, while $address_pipe contains the
text of the pipe command itself.

A "pipe" transport can also be used from a router as a pseudo-remote
transport for passing messages for remote delivery by some means other
than Exim.

As "pipe" is a local transport, it is always run in a separate process,
normally under a non-privileged uid and gid. In the common case, these
are the uid and gid belonging to the user whose `.forward' file
directed the message at the pipe. In other cases the uid and gid have
to be specified explicitly, either on the transport or on the director
or router that handled the address.  Current and `home' directories are
also controllable. See chapter "Environment for running local
transports" for details of the local delivery environment.



* Menu:

* Returned status and data::
* How the command is run::
* Environment variables::
* Private options for pipe::
* Using an external local delivery agent::


File: exim.info,  Node: Returned status and data,  Next: How the command is run,  Prev: The pipe transport,  Up: The pipe transport

Returned status and data
========================

If the command exits with a non-zero return code, the delivery is
deemed to have failed, unless either the "ignore_status" option is set
(in which case the return code is treated as zero), or the return code
is one of those listed in the "temp_errors" option, which are
interpreted as meaning `try again later'.  In this case, delivery is
deferred.

If the return code is greater than 128 and the command being run is a
shell script, it normally means that the script was terminated by a
signal whose value is the return code minus 128.

The "return_output" option can affect the result of a pipe delivery. If
it is set and the command produces any output on its standard output or
standard error files, it is considered to have failed, even if it gave
a zero return code or if "ignore_status" is set. The output from the
command is sent as part of the delivery failure report. However, if
"return_fail_output" is set, output is returned only when the command
exits with a failure return code, that is, a value other than zero or a
code that matches "temp_errors".


File: exim.info,  Node: How the command is run,  Next: Environment variables,  Prev: Returned status and data,  Up: The pipe transport

How the command is run
======================

The command line is (by default) broken down into a command name and
arguments by the "pipe" transport. The "allow_commands" and
"restrict_to_path" options can be used to restrict the commands that
may be run.  Unquoted arguments are delimited by white space; in
double-quoted arguments, backslash is interpreted as an escape
character in the usual way. This does not happen for single-quoted
arguments.

String expansion is applied to the command line except when it comes
from a traditional `.forward' file (commands from a filter file are
expanded). The expansion is applied to each argument in turn rather
than to the whole line.  For this reason, any string expansion item
that contains white space must be quoted so as to be contained within a
single argument. A setting such as

     command = /some/path ${if eq{$local_part}{postmaster}{xxx}{yyy}}

will not work, because the expansion item gets split between several
arguments. You have to write

     command = /some/path "${if eq{$local_part}{postmaster}{xxx}{yyy}}"

to ensure that it is all in one argument. If the whole command line is
quoted, then the internal quotes have to be escaped with backslashes
(or single quotes can be used). The expansion is done in this way,
argument by argument, so that the number of arguments cannot be changed
as a result, and quotes or backslashes in inserted variables do not
interact with external quoting.

Special handling takes place when an argument consists precisely of the
text `$pipe_addresses'. This is not a general expansion variable; the
only place this string is recognized is when it appears as an argument
for a pipe or transport filter command. It causes each address that is
being handled to be inserted in the argument list at that point as a
separate argument. This avoids any problems with spaces or shell
metacharacters, and is of use when a "pipe" transport is handling
groups of addresses in a batch (see the "batch" option below).

The resulting command is then run in a subprocess directly from the
transport, not under a shell, with the message supplied on the standard
input, and the standard output and standard error both connected to a
single pipe that is read by Exim. The "max_output" option controls how
much output the command may produce, and the "return_output" and
"return_fail_output" options control what is done with it.

Not running the command under a shell (by default) lessens the security
risks in cases when a command from a user's filter file is built out of
data that was taken from an incoming message. If a shell is required,
it can of course be explicitly specified as the command to be run.
However, there are circumstances where existing commands (for example,
in `.forward' files) expect to be run under a shell and cannot easily
be modified. To allow for these cases, there is an option called
"use_shell", which changes the way the "pipe" transport works. Instead
of breaking up the command line as just described, it expands it as a
single string and passes the result to "/bin/sh". The "restrict_to_path"
option and the $pipe_addresses facility cannot be used with "use_shell",
and the whole mechanism is inherently less secure.


File: exim.info,  Node: Environment variables,  Next: Private options for pipe,  Prev: How the command is run,  Up: The pipe transport

Environment variables
=====================

The following environment variables are set up when the command is
invoked:

     DOMAIN               the local domain of the address
     HOME                 the `home' directory -- see below
     HOST                 the host name when called from a router
     LOCAL_PART           see below
     LOGNAME              see below
     MESSAGE_ID           the message's id
     PATH                 as specified by the "path" option below
     QUALIFY_DOMAIN       the configured qualification domain
     SENDER               the sender of the message
     SHELL                /bin/sh
     USER                 see below

The "environment" option can be used to add additional variables to this
environment.

When a "pipe" transport is called directly from (for example) a
"smartuser" director, LOCAL_PART is set to the local part of the
address. When it is called as a result of a forward or alias expansion,
LOCAL_PART is set to the local part of the address that was expanded.
LOGNAME and USER are set to the same value as LOCAL_PART for
compatibility with other MTAs.

HOST is set only when a "pipe" transport is called from a router as a
pseudo-remote transport (for example, for handling batched SMTP). It is
set to the first host name specified by the router (if any).

If the transport's "home_directory" option is set, its value is used for
the HOME environment variable. Otherwise, certain directors may set a
home directory value, as described in chapter "Environment for running
local transports".


File: exim.info,  Node: Private options for pipe,  Next: Using an external local delivery agent,  Prev: Environment variables,  Up: The pipe transport

Private options for pipe
========================



* Menu:

* allow_commands (pipe)::
* batch (pipe)::
* batch_max (pipe)::
* bsmtp (pipe)::
* bsmtp_helo (pipe)::
* check_string (pipe)::
* command (pipe)::
* current_directory (pipe)::
* environment (pipe)::
* escape_string (pipe)::
* freeze_exec_fail (pipe)::
* from_hack (pipe)::
* group (pipe)::
* home_directory (pipe)::
* ignore_status (pipe)::
* initgroups (pipe)::
* log_defer_output (pipe)::
* log_fail_output (pipe)::
* log_output (pipe)::
* max_output (pipe)::
* path (pipe)::
* pipe_as_creator (pipe)::
* prefix (pipe)::
* restrict_to_path (pipe)::
* retry_use_local_part (pipe)::
* return_fail_output (pipe)::
* return_output (pipe)::
* suffix (pipe)::
* temp_errors (pipe)::
* timeout (pipe)::
* umask (pipe)::
* use_crlf (pipe)::
* use_shell (pipe)::
* user (pipe)::


File: exim.info,  Node: allow_commands (pipe),  Next: batch (pipe),  Prev: Private options for pipe,  Up: Private options for pipe

allow_commands (pipe) _option_
------------------------------

Type: string list, expanded
Default: unset

The string is expanded, and then is interpreted as a colon-separated
list of permitted commands. If "restrict_to_path" is not set, the only
commands permitted are those in the "allow_commands" list. They need
not be absolute paths; the "path" option is still used for relative
paths. If "restrict_to_path" is set with "allow_commands", the command
must either be in the "allow_commands" list, or a name without any
slashes that is found on the path. In other words, if neither
"allow_commands" nor "restrict_to_path" is set, there is no restriction
on the command, but otherwise only commands that are permitted by one
or the other are allowed. For example, if

     allow_commands = /usr/ucb/vacation

and "restrict_to_path" is not set, the only permitted command is
"/usr/ucb/vacation". The "allow_commands" option may not be set if
"use_shell" is set.


File: exim.info,  Node: batch (pipe),  Next: batch_max (pipe),  Prev: allow_commands (pipe),  Up: Private options for pipe

batch (pipe) _option_
---------------------

Type: string
Default: "none"

Normally, each address that is directed or routed to a "pipe" transport
is handled separately. In special cases it may be desirable to handle
several addresses at once, for example, when passing a message with
several addresses to a different mail regime (for example, UUCP). If
this option is set to the string `domain', all addresses with the same
domain that are directed or routed to the transport are handled in a
single delivery. If it is set to `all', multiple domains are batched.
The list of addresses is included in the "Envelope-to:" header if
"envelope_to_add" is set. The addresses can also be set up as separate
arguments to the pipe command by means of the specially-recognized
argument $pipe_addresses (see above). Otherwise, the only difference
between this option and "bsmtp" is the inclusion of SMTP command lines
in the output for "bsmtp". When more than one address is being
delivered, $local_part is not set, and $domain is set only if they all
have the same domain.


File: exim.info,  Node: batch_max (pipe),  Next: bsmtp (pipe),  Prev: batch (pipe),  Up: Private options for pipe

batch_max (pipe) _option_
-------------------------

Type: integer
Default: 100

This limits the number of addresses that can be handled in a batch, and
applies to both the "batch" and the "bsmtp" options.


File: exim.info,  Node: bsmtp (pipe),  Next: bsmtp_helo (pipe),  Prev: batch_max (pipe),  Up: Private options for pipe

bsmtp (pipe) _option_
---------------------

Type: string
Default: "none"

This option is used to set up a "pipe" transport as a pseudo-remote
transport for delivering messages in batch SMTP format for onward
transmission by some non-Exim means. The value of the option must be
one of the strings `none', `one', `domain', or `all'. The first of
these turns the feature off. When "bstmp" is set, the "batch" option
automatically takes the same value.  The "check_string" and
"escape_string" options are forced to the values

     check_string = "."
     escape_string = ".."

when batched SMTP is in use.  It is usually necessary to suppress the
default settings of the "prefix" and "suffix" options. A full
description of the batch SMTP mechanism is given in section "Outgoing
batched SMTP" in chapter "SMTP processing". See also the "use_crlf"
option.


File: exim.info,  Node: bsmtp_helo (pipe),  Next: check_string (pipe),  Prev: bsmtp (pipe),  Up: Private options for pipe

bsmtp_helo (pipe) _option_
--------------------------

Type: boolean
Default: false

When this option is set, a HELO line is added to the output at the
start of each message written in batch SMTP format. Some software that
reads batch SMTP is unhappy without this.


File: exim.info,  Node: check_string (pipe),  Next: command (pipe),  Prev: bsmtp_helo (pipe),  Up: Private options for pipe

check_string (pipe) _option_
----------------------------

Type: string
Default: unset

As "pipe" writes the message, the start of each line is tested for
matching "check_string", and if it does, the initial matching
characters are replaced by the contents of "escape_string", provided
both are set. The value of "check_string" is a literal string, not a
regular expression, and the case of any letters it contains is
significant.  When the "bsmtp" option is set, the contents of
"check_string" and "escape_string" are forced to values that implement
the SMTP escaping protocol. Any settings made in the configuration file
are ignored.


File: exim.info,  Node: command (pipe),  Next: current_directory (pipe),  Prev: check_string (pipe),  Up: Private options for pipe

command (pipe) _option_
-----------------------

Type: string, expanded
Default: unset

This option need not be set when "pipe" is being used to deliver to
pipes obtained from address expansions (usually under the instance name
"address_pipe"). In other cases, the option must be set, to provide a
command to be run. It need not yield an absolute path (see the "path"
option below).  The command is split up into separate arguments by
Exim, and each argument is separately expanded, as described in section
"How the command is run" above.


File: exim.info,  Node: current_directory (pipe),  Next: environment (pipe),  Prev: command (pipe),  Up: Private options for pipe

current_directory (pipe) _option_
---------------------------------

Type: string, expanded
Default: unset

If this option is set, it specifies the directory to make current when
running the delivery process. The string is expanded at the time the
transport is run.  If this is not set, the current directory is taken
from data associated with the address. See chapter "Environment for
running local transports" for full details of the local delivery
environment.


File: exim.info,  Node: environment (pipe),  Next: escape_string (pipe),  Prev: current_directory (pipe),  Up: Private options for pipe

environment (pipe) _option_
---------------------------

Type: string, expanded
Default: unset

This option is used to add additional variables to the environment in
which the command runs (see section "Environment variables" for the
default list). Its value is a string which is expanded, and then
interpreted as a colon-separated list of environment settings of the
form `<name>=<value>'.


File: exim.info,  Node: escape_string (pipe),  Next: freeze_exec_fail (pipe),  Prev: environment (pipe),  Up: Private options for pipe

escape_string (pipe) _option_
-----------------------------

Type: string
Default: unset

See "check_string" above.


File: exim.info,  Node: freeze_exec_fail (pipe),  Next: from_hack (pipe),  Prev: escape_string (pipe),  Up: Private options for pipe

freeze_exec_fail (pipe) _option_
--------------------------------

Type: boolean
Default: false

Failure to exec the command in a pipe transport is by default treated
like any other failure while running the command. However, if
"freeze_exec_fail" is set, failure to exec is treated specially, and
causes the message to be frozen, whatever the setting of
"ignore_status".


File: exim.info,  Node: from_hack (pipe),  Next: group (pipe),  Prev: freeze_exec_fail (pipe),  Up: Private options for pipe

from_hack (pipe) _option_
-------------------------

Type: boolean
Default: false

This option is obsolete and is retained only for backwards
compatibility. Its value is ignored. It has been replaced by
"check_string" and "escape_string".


File: exim.info,  Node: group (pipe),  Next: home_directory (pipe),  Prev: from_hack (pipe),  Up: Private options for pipe

group (pipe) _option_
---------------------

Type: string
Default: unset

If this option is set, it specifies the group under whose gid the
delivery process is to be run. If it is not set, a value associated
with a user may be used (see below); otherwise a value must have been
associated with the address by the director which handled it. If the
string contains no $ characters, it is resolved when Exim starts up.
Otherwise, the string is expanded at the time the transport is run, and
must yield either a digit string or a name which can be looked up using
"getgrnam()".


File: exim.info,  Node: home_directory (pipe),  Next: ignore_status (pipe),  Prev: group (pipe),  Up: Private options for pipe

home_directory (pipe) _option_
------------------------------

Type: string, expanded
Default: unset

If this option is set, its expanded value is used to set the HOME
environment variable before running the command. This overrides any
value that is set by the director. If no current directory is supplied
by the director or the transport, the home directory value is used for
that as well. See chapter "Environment for running local transports"
for details of the local delivery environment.


File: exim.info,  Node: ignore_status (pipe),  Next: initgroups (pipe),  Prev: home_directory (pipe),  Up: Private options for pipe

ignore_status (pipe) _option_
-----------------------------

Type: boolean
Default: false

If this option is true, the status returned by the subprocess that is
set up to run the command is ignored, and Exim behaves as if zero had
been returned.  Otherwise, a non-zero status causes an error return
from the transport unless the value is EX_TEMPFAIL, which causes the
delivery to be deferred and tried again later.


File: exim.info,  Node: initgroups (pipe),  Next: log_defer_output (pipe),  Prev: ignore_status (pipe),  Up: Private options for pipe

initgroups (pipe) _option_
--------------------------

Type: boolean
Default: false

If this option is true and the uid for the local delivery is specified
by the "user" option, then the "initgroups()" function is called when
running the transport to ensure that any additional groups associated
with the uid are set up.


File: exim.info,  Node: log_defer_output (pipe),  Next: log_fail_output (pipe),  Prev: initgroups (pipe),  Up: Private options for pipe

log_defer_output (pipe) _option_
--------------------------------

Type: boolean
Default: false

If this option is set, and the status returned by the command is one of
the codes listed in "temp_errors" (that is, delivery was deferred), and
any output was produced, the first line of it is written to the main
log.


File: exim.info,  Node: log_fail_output (pipe),  Next: log_output (pipe),  Prev: log_defer_output (pipe),  Up: Private options for pipe

log_fail_output (pipe) _option_
-------------------------------

Type: boolean
Default: false

If this option is set, and the command returns any output, and also
ends with a return code that is neither zero nor one of the return
codes listed in "temp_errors" (that is, the delivery failed), the first
line of output is written to the main log.


File: exim.info,  Node: log_output (pipe),  Next: max_output (pipe),  Prev: log_fail_output (pipe),  Up: Private options for pipe

log_output (pipe) _option_
--------------------------

Type: boolean
Default: false

If this option is set and the command returns any output, the first
line of output is written to the main log, whatever the return code.


File: exim.info,  Node: max_output (pipe),  Next: path (pipe),  Prev: log_output (pipe),  Up: Private options for pipe

max_output (pipe) _option_
--------------------------

Type: integer
Default: 20K

This specifies the maximum amount of output that the command may
produce on its standard output and standard error file combined.  If
the limit is exceeded, the process running the command is killed. This
is intended as a safety measure to catch runaway processes. The limit
is applied whether any "return_output" option is set or not. Because of
buffering effects, the amount of output may exceed the limit by a small
amount before Exim notices.


File: exim.info,  Node: path (pipe),  Next: pipe_as_creator (pipe),  Prev: max_output (pipe),  Up: Private options for pipe

path (pipe) _option_
--------------------

Type: string list
Default: "/usr/bin"

This option specifies the string that is set up in the PATH environment
variable of the subprocess.  If the "command" option does not yield an
absolute path name, the command is sought in the PATH directories, in
the usual way.


File: exim.info,  Node: pipe_as_creator (pipe),  Next: prefix (pipe),  Prev: path (pipe),  Up: Private options for pipe

pipe_as_creator (pipe) _option_
-------------------------------

Type: boolean
Default: false

If "user" is not set and this option is true, the delivery process is
run under the uid that was in force when Exim was originally called to
accept the message. If the group id is not otherwise set (via the
"group" option above, or by the director that processed the address),
the gid that was in force when Exim was originally called to accept the
message is used. Setting this option may be necessary in order to get
some free-standing local delivery agents to work correctly. Note,
however, that the "never_users" configuration option overrides.


File: exim.info,  Node: prefix (pipe),  Next: restrict_to_path (pipe),  Prev: pipe_as_creator (pipe),  Up: Private options for pipe

prefix (pipe) _option_
----------------------

Type: string, expanded
Default: see below

The string specified here is expanded and output at the start of every
message.  The default is the same as for the "appendfile" transport,
namely

     prefix = "From ${if def:return_path{$return_path}{MAILER-DAEMON}}\
       ${tod_bsdinbox}\n"

This is required by the commonly used "/usr/ucb/vacation" program, but
it must not be present if delivery is to the Cyrus IMAP server, or to
the "tmail" local delivery agent.  The prefix can be suppressed by
setting

     prefix =

This is also usually necessary when doing batch SMTP deliveries.


File: exim.info,  Node: restrict_to_path (pipe),  Next: retry_use_local_part (pipe),  Prev: prefix (pipe),  Up: Private options for pipe

restrict_to_path (pipe) _option_
--------------------------------

Type: boolean
Default: false

When this option is set, any command name not listed in "allow_commands"
must contain no slashes. The command is searched for only in the
directories listed in the "path" option. This option is intended for
use in the case when a pipe command has been generated from a user's
`.forward' file. This is usually handled by a "pipe" transport called
"address_pipe".


File: exim.info,  Node: retry_use_local_part (pipe),  Next: return_fail_output (pipe),  Prev: restrict_to_path (pipe),  Up: Private options for pipe

retry_use_local_part (pipe) _option_
------------------------------------

Type: boolean
Default: true

When a local delivery suffers a temporary failure, both the local part
and the domain are normally used to form a key that is used to
determine when next to try the address. This handles common cases such
as exceeding a quota, where the failure applies to the specific local
part. However, when local delivery is being used to collect messages
for onward transmission by some other means, a temporary failure may
not depend on the local part at all. Setting this option false causes
Exim to use only the domain when handling retries for this transport.


File: exim.info,  Node: return_fail_output (pipe),  Next: return_output (pipe),  Prev: retry_use_local_part (pipe),  Up: Private options for pipe

return_fail_output (pipe) _option_
----------------------------------

Type: boolean
Default: false

If this option is true, and the command produced any output and ended
with a return code other than zero or one of the codes listed in
"temp_errors" (that is, the delivery failed), the output is returned in
the delivery error message. However, if the message has a null sender
(that is, it is itself a delivery error message), output from the
command is discarded.


File: exim.info,  Node: return_output (pipe),  Next: suffix (pipe),  Prev: return_fail_output (pipe),  Up: Private options for pipe

return_output (pipe) _option_
-----------------------------

Type: boolean
Default: false

If this option is true, and the command produced any output, the
delivery is deemed to have failed whatever the return code from the
command, and the output is returned in the delivery error message.
Otherwise, the output is just discarded. However, if the message has a
null sender (that is, it is a delivery error message), output from the
command is always discarded, whatever the setting of this option.


File: exim.info,  Node: suffix (pipe),  Next: temp_errors (pipe),  Prev: return_output (pipe),  Up: Private options for pipe

suffix (pipe) _option_
----------------------

Type: string, expanded
Default: "\n"

The string specified here is expanded and output at the end of every
message.  The default is the same as for the "appendfile" transport.
It can be suppressed by setting

     suffix =

and this is usually necessary when doing batch SMTP deliveries.


File: exim.info,  Node: temp_errors (pipe),  Next: timeout (pipe),  Prev: suffix (pipe),  Up: Private options for pipe

temp_errors (pipe) _option_
---------------------------

Type: string
Default: see below

This option contains a colon-separated list of numbers. If
"ignore_status" is false and the command exits with a return code that
matches one of the numbers, the failure is treated as temporary and the
delivery is deferred. The default setting contains the codes defined by
EX_TEMPFAIL and EX_CANTCREAT in "sysexits.h". If Exim is compiled on a
system that does not define these macros, it assumes values of 75 and
73, respectively.


File: exim.info,  Node: timeout (pipe),  Next: umask (pipe),  Prev: temp_errors (pipe),  Up: Private options for pipe

timeout (pipe) _option_
-----------------------

Type: time
Default: 1h

If the command fails to complete within this time, it is killed. This
normally causes the delivery to fail.  A zero time interval specifies
no timeout. In order to ensure that any subprocesses created by the
command are also killed, Exim makes the initial process a process group
leader, and kills the whole process group on a timeout.  However, this
can be defeated if one of the processes starts a new process group.


File: exim.info,  Node: umask (pipe),  Next: use_crlf (pipe),  Prev: timeout (pipe),  Up: Private options for pipe

umask (pipe) _option_
---------------------

Type: octal integer
Default: 022

This specifies the umask setting for the subprocess that runs the
command.


File: exim.info,  Node: use_crlf (pipe),  Next: use_shell (pipe),  Prev: umask (pipe),  Up: Private options for pipe

use_crlf (pipe) _option_
------------------------

Type: boolean
Default: false

This option causes lines to be terminated with the two-character CRLF
sequence (carriage return, linefeed) instead of just a linefeed
character. In the case of batched SMTP, the byte sequence written to
the pipe is then an exact image of what would be sent down a real SMTP
connection.

The contents of the "prefix" and "suffix" options are written verbatim,
so must contain their own carriage return characters if these are
needed. Since the default values for both "prefix" and "suffix" end
with a single linefeed, their values almost always need to be changed
if "use_crlf" is set.


File: exim.info,  Node: use_shell (pipe),  Next: user (pipe),  Prev: use_crlf (pipe),  Up: Private options for pipe

use_shell (pipe) _option_
-------------------------

Type: boolean
Default: false

If this option is set, it causes the command to be passed to "/bin/sh"
instead of being run directly from the transport as described in section
"How the command is run". This is less secure, but is needed in some
situations where the command is expected to be run under a shell and
cannot easily be modified. The "allow_commands" and "restrict_to_path"
options, and the `$pipe_addresses' facility are incompatible with
"use_shell". The command is expanded as a single string, and handed to
"/bin/sh" as data for its -c option.


File: exim.info,  Node: user (pipe),  Prev: use_shell (pipe),  Up: Private options for pipe

user (pipe) _option_
--------------------

Type: string
Default: unset

If this option is set, it specifies the user under whose uid the
delivery process is to be run. If it is not set, a value must have been
associated with the address by the director that handled it. If the
string contains no $ characters, it is resolved when Exim starts up.
Otherwise, the string is expanded at the time the transport is run, and
must yield either a digit string or a name which can be looked up using
"getpwnam()". When "getpwnam()" is used, either at start-up time or
later, the group id value associated with the user is taken as the
value to be used if the "group" option is not set.


File: exim.info,  Node: Using an external local delivery agent,  Prev: Private options for pipe,  Up: The pipe transport

Using an external local delivery agent
======================================

The "pipe" transport can be used to pass all messages that require local
delivery to a separate local delivery agent such as "procmail". When
doing this, care must be taken to ensure that the pipe is run under an
appropriate uid and gid. In some configurations one wants this to be a
uid that is trusted by the delivery agent to supply the correct sender
of the message. It may be necessary to recompile or reconfigure the
delivery agent so that it trusts an appropriate user. The following is
an example transport and director configuration for "procmail":

     # transport
     procmail_pipe:
       driver = pipe
       command = /opt/local/bin/procmail -d $local_part
       return_path_add
       delivery_date_add
       envelope_to_add
       check_string = "From "
       escape_string = ">From "
       user = $local_part
       group = mail


     # director
     procmail:
       driver = localuser
       transport = procmail_pipe

In this example, the pipe is run as the local user, but with the group
set to "mail". An alternative is to run the pipe as a specific user
such as "mail" or "exim", but in this case you must arrange for
"procmail" to trust that user to supply a correct sender address.  If
you don't specify either a "group" or a "user" option, the pipe command
is run as the local user. The home directory is the user's home
directory by default.

Note that the command that the pipe transport runs does not begin with

     IFS=" "

as shown in the "procmail" documentation, because Exim does not by
default use a shell to run pipe commands.

The next example shows a transport and a director for a system where
local deliveries are handled by the Cyrus IMAP server.

     # transport
     local_delivery_cyrus:
       driver = pipe
       command = /usr/cyrus/bin/deliver \
                 -m ${substr_1:$local_part_suffix} -- $local_part
       user = cyrus
       group = mail
       return_output
       log_output
       prefix =
       suffix =


     # director
     local_user_cyrus:
       driver = localuser
       suffix = .*
       transport = local_delivery_cyrus

Note the unsetting of "prefix" and "suffix", and the use of
"return_output" to cause any text written by Cyrus to be returned to
the sender.


File: exim.info,  Node: The smtp transport,  Next: Generic options common to both directors and routers,  Prev: The pipe transport,  Up: Top

The smtp transport
******************

The "smtp" transport delivers messages over TCP/IP connections using
the SMTP protocol. The list of hosts to try can either be taken from
the address that is being processed, or specified explicitly for the
transport. Timeout and retry processing (see chapter "Retry
configuration") is applied to each IP address independently. The
private options are as follows:



* Menu:

* allow_localhost (smtp)::
* authenticate_hosts (smtp)::
* batch_max (smtp)::
* command_timeout (smtp)::
* connect_timeout (smtp)::
* data_timeout (smtp)::
* delay_after_cutoff (smtp)::
* dns_qualify_single (smtp)::
* dns_search_parents (smtp)::
* fallback_hosts (smtp)::
* final_timeout (smtp)::
* gethostbyname (smtp)::
* helo_data (smtp)::
* hosts (smtp)::
* hosts_avoid_tls (smtp)::
* hosts_require_tls (smtp)::
* hosts_override (smtp)::
* hosts_max_try (smtp)::
* hosts_randomize (smtp)::
* interface (smtp)::
* keepalive (smtp)::
* max_rcpt (smtp)::
* multi_domain (smtp)::
* mx_domains (smtp)::
* port (smtp)::
* protocol (smtp)::
* retry_include_ip_address (smtp)::
* serialize_hosts (smtp)::
* service (smtp)::
* size_addition (smtp)::
* tls_certificate (smtp)::
* tls_privatekey (smtp)::
* tls_verify_certificates (smtp)::
* tls_verify_ciphers (smtp)::


File: exim.info,  Node: allow_localhost (smtp),  Next: authenticate_hosts (smtp),  Prev: The smtp transport,  Up: The smtp transport

allow_localhost (smtp) _option_
-------------------------------

Type: boolean
Default: false

When a host specified in "hosts" or "fallback_hosts" (see below) turns
out to be the local host, or is listed in "hosts_treat_as_local", Exim
freezes the message by default. However, if "allow_localhost" is set,
it goes on to do the delivery anyway. This should be used only in
special cases when the configuration ensures that no looping will
result (for example, a differently configured Exim is listening on the
SMTP port).


File: exim.info,  Node: authenticate_hosts (smtp),  Next: batch_max (smtp),  Prev: allow_localhost (smtp),  Up: The smtp transport

authenticate_hosts (smtp) _option_
----------------------------------

Type: host list
Default: unset

This option is available only when Exim is built to contain support for
at least one of the SMTP authentication mechanisms. It provides a list
of servers to which, provided they announce authentication support,
Exim will attempt to authenticate as a client when it connects. See
chapter "SMTP authentication" for details.


File: exim.info,  Node: batch_max (smtp),  Next: command_timeout (smtp),  Prev: authenticate_hosts (smtp),  Up: The smtp transport

batch_max (smtp) _option_
-------------------------

Type: integer
Default: 500

This controls the maximum number of separate message deliveries that
can take place over a single TCP/IP connection. If the value is zero,
there is no limit.

When a message has been successfully delivered over a TCP/IP
connection, Exim looks in its hints database to see if there are any
other messages awaiting a connection to the same host. If there are, a
new delivery process is started for one of them, and the current TCP/IP
connection is passed on to it. The new process may in turn create yet
another process. Each time this happens, a sequence counter is
incremented, and if it ever gets to the (non-zero) "batch_max" value,
no further messages are sent on the same TCP/IP connection.

For testing purposes, this value can be overridden by the -oB command
line option.


File: exim.info,  Node: command_timeout (smtp),  Next: connect_timeout (smtp),  Prev: batch_max (smtp),  Up: The smtp transport

command_timeout (smtp) _option_
-------------------------------

Type: time
Default: 5m

This sets a timeout for receiving a response to an SMTP command that
has been sent out. It is also used when waiting for the initial banner
line from the remote host. Its value must not be zero.


File: exim.info,  Node: connect_timeout (smtp),  Next: data_timeout (smtp),  Prev: command_timeout (smtp),  Up: The smtp transport

connect_timeout (smtp) _option_
-------------------------------

Type: time
Default: 5m

This sets a timeout for the "connect()" function, which sets up a
TCP/IP call to a remote host. A setting of zero allows the system
timeout (typically several minutes) to act. To have any effect, the
value of this option must be less than the system timeout. However, it
has been observed that on some systems there is no system timeout,
which is why the default value for this option is 5 minutes, a value
recommended by RFC 1123.


File: exim.info,  Node: data_timeout (smtp),  Next: delay_after_cutoff (smtp),  Prev: connect_timeout (smtp),  Up: The smtp transport

data_timeout (smtp) _option_
----------------------------

Type: time
Default: 5m

This sets a timeout for the transmission of each block in the data
portion of the message. As a result, the overall timeout for a message
depends on the size of the message. Its value must not be zero. See
also "final_timeout".


File: exim.info,  Node: delay_after_cutoff (smtp),  Next: dns_qualify_single (smtp),  Prev: data_timeout (smtp),  Up: The smtp transport

delay_after_cutoff (smtp) _option_
----------------------------------

Type: boolean
Default: true

This option controls what happens when all remote IP addresses for a
given domain have been inaccessible for so long that they have passed
their retry cutoff times.

In the default state, if the next retry time has not been reached for
any of them, the address is bounced without trying any deliveries. In
other words, Exim delays retrying an IP address after the final cutoff
time until a new retry time is reached, and can therefore bounce an
address without ever trying a delivery, when machines have been down
for a long time. Some people are unhappy at this prospect, so...

If "delay_after_cutoff" is set false, Exim behaves differently. If all
IP addresses are past their final cutoff time, Exim tries to deliver to
those IP addresses that have not been tried since the message arrived.
If there are none, of if they all fail, the address is bounced. In
other words, it does not delay when a new message arrives, but
immediately tries those expired IP addresses that haven't been tried
since the message arrived. If there is a continuous stream of messages
for the dead hosts, unsetting "delay_after_cutoff" means that there
will be many more attempts to deliver to them.


File: exim.info,  Node: dns_qualify_single (smtp),  Next: dns_search_parents (smtp),  Prev: delay_after_cutoff (smtp),  Up: The smtp transport

dns_qualify_single (smtp) _option_
----------------------------------

Type: boolean
Default: true

If the "hosts" or "fallback_hosts" option is being used and names are
being looked up in the DNS, the option to cause the resolver to qualify
single-component names with the local domain is set.


File: exim.info,  Node: dns_search_parents (smtp),  Next: fallback_hosts (smtp),  Prev: dns_qualify_single (smtp),  Up: The smtp transport

dns_search_parents (smtp) _option_
----------------------------------

Type: boolean
Default: false

If the "hosts" or "fallback_hosts" option is being used and names are
being looked up in the DNS, the resolver option to enable the searching
of parent domains is set. Many resolvers default this option to be on,
but its use in resolving mail addresses has caused problems in cases
where wildcard MX records exist, so the default was changed to false in
Exim version 1.80.


File: exim.info,  Node: fallback_hosts (smtp),  Next: final_timeout (smtp),  Prev: dns_search_parents (smtp),  Up: The smtp transport

fallback_hosts (smtp) _option_
------------------------------

Type: string list
Default: unset

String expansion is not applied to this option. The argument must be a
colon-separated list of host names or IP addresses. Fallback hosts can
also be specified on routers and directors which then associate them
with the addresses they process; as for the "hosts" option without
"hosts_override", "fallback_hosts" specified on the transport is used
only if the address does not have its own associated fallback host
list. Unlike "hosts", a setting of "fallback_hosts" on an address is
not overridden by "hosts_override", and neither does "hosts_randomize"
apply to fallback host lists.

If Exim is unable to deliver to any of the hosts for a particular
address, and the errors are not permanent rejections, the address is
put on a separate transport queue with its host list replaced by the
fallback hosts, unless the address was routed via MX records and the
current host was in the original MX list. In that situation, the
fallback host list is not used.

Once normal deliveries are complete, the fallback queue is delivered by
re-running the same transports with the new host lists. If several
failing addresses have the same fallback hosts (and "max_rcpt" permits
it), a single copy of the message is sent.

The resolution of the host names on the fallback list is controlled by
the "gethostbyname()" and "mx_domains" options, as for the "hosts"
option.  Fallback hosts apply both to cases when the host list comes
with the address and when it is taken from "hosts". This option
provides a `use a smart host only if delivery fails' facility.


File: exim.info,  Node: final_timeout (smtp),  Next: gethostbyname (smtp),  Prev: fallback_hosts (smtp),  Up: The smtp transport

final_timeout (smtp) _option_
-----------------------------

Type: time
Default: 10m

This is the timeout that applies while waiting for the response to the
final line containing just `.' that terminates a message. Its value
must not be zero.


File: exim.info,  Node: gethostbyname (smtp),  Next: helo_data (smtp),  Prev: final_timeout (smtp),  Up: The smtp transport

gethostbyname (smtp) _option_
-----------------------------

Type: boolean
Default: false

If this option is true when the "hosts" and/or "fallback_hosts" options
are being used, names are looked up using "gethostbyname()" instead of
using the DNS with MX processing.  Of course, "gethostbyname()" may in
fact use the DNS to look up A (but not MX) records, but it may also
consult other sources of information such as "/etc/hosts".


File: exim.info,  Node: helo_data (smtp),  Next: hosts (smtp),  Prev: gethostbyname (smtp),  Up: The smtp transport

helo_data (smtp) _option_
-------------------------

Type: string, expanded
Default: "$primary_hostname"

The value of this option is expanded, and used as the argument for the
EHLO or HELO command that starts the outgoing SMTP session.


File: exim.info,  Node: hosts (smtp),  Next: hosts_avoid_tls (smtp),  Prev: helo_data (smtp),  Up: The smtp transport

hosts (smtp) _option_
---------------------

Type: string list, expanded
Default: unset

Hosts are associated with an address by a router such as "lookuphost",
which finds the hosts by looking up the address domain in the DNS.
However, addresses can be passed to the "smtp" transport by any router
or director, not all of which provide an associated host list. This
option specifies a list of hosts which are used if the address being
processed does not have any hosts associated with it, or if the
"hosts_override" option is set.

The string is first expanded, before being interpreted as a
colon-separated list of host names or IP addresses.  If the expansion
fails, delivery is deferred. Unless the failure was caused by the
inability to complete a lookup, the error is logged to the panic log as
well as the main log.  Host names are looked up either in the DNS
(using MX processing) or using "gethostbyname()", depending on the
setting of the "gethostbyname" option. When Exim is compiled with IPv6
support, if a host that is looked up in the DNS has both A and AAAA or
A6 records, all the addresses are used.

This option is typically used in association with a "smartuser"
director that wants to direct messages to a particular host or hosts.
The given hosts are tried in order, subject to their retry status. This
option is ignored when the address has been routed by a router that
supplies a host list (for example, "lookuphost"), unless
"hosts_override" is set.


File: exim.info,  Node: hosts_avoid_tls (smtp),  Next: hosts_require_tls (smtp),  Prev: hosts (smtp),  Up: The smtp transport

hosts_avoid_tls (smtp) _option_
-------------------------------

Type: host list
Default: unset

Exim will not try to start a TLS session when delivering to any host
that matches this list. See chapter "Encrypted SMTP connections using
TLS/SSL" for details of TLS.


File: exim.info,  Node: hosts_require_tls (smtp),  Next: hosts_override (smtp),  Prev: hosts_avoid_tls (smtp),  Up: The smtp transport

hosts_require_tls (smtp) _option_
---------------------------------

Type: host list
Default: unset

Exim will insist on using a TLS session when delivering to any host that
matches this list. See chapter "Encrypted SMTP connections using
TLS/SSL" for details of TLS.


File: exim.info,  Node: hosts_override (smtp),  Next: hosts_max_try (smtp),  Prev: hosts_require_tls (smtp),  Up: The smtp transport

hosts_override (smtp) _option_
------------------------------

Type: boolean
Default: false

If this option is set and the "hosts" option is also set, any hosts that
are attached to the address are ignored, and instead the hosts
specified by the "hosts" option are always used.  This option does not
apply to "fallback_hosts".


File: exim.info,  Node: hosts_max_try (smtp),  Next: hosts_randomize (smtp),  Prev: hosts_override (smtp),  Up: The smtp transport

hosts_max_try (smtp) _option_
-----------------------------

Type: integer
Default: 5

This option limits the number of IP addresses that will be tried for
any one delivery. Some large domains have very many MX records, each of
which may refer to several IP addresses. Trying every single one of
such a long list does not seem sensible; if several at the top of the
list fail, it is reasonable to assume there is some problem that is
likely to affect all of them. The value of "hosts_max_try" is the
maximum number of IP addresses that will actually be tried; any that
are skipped because their retry times have not arrived do not count.


File: exim.info,  Node: hosts_randomize (smtp),  Next: interface (smtp),  Prev: hosts_max_try (smtp),  Up: The smtp transport

hosts_randomize (smtp) _option_
-------------------------------

Type: boolean
Default: false

If this option is set on an "smtp" transport that uses its hosts list,
the order of items in the list is randomized each time it is used. This
does not apply to "fallback_hosts".


File: exim.info,  Node: interface (smtp),  Next: keepalive (smtp),  Prev: hosts_randomize (smtp),  Up: The smtp transport

interface (smtp) _option_
-------------------------

Type: string
Default: unset

This option specifies which interface to bind to when making an
outgoing SMTP call. The string must be an IP address, for example:

     interface = 192.168.123.123

If "interface" is not set, the system's IP functions choose which
interface to use if there is more than one. In an IPv6 system, the type
of interface specified must be of the same kind as the address to which
the call is being made. If not, it is ignored.


File: exim.info,  Node: keepalive (smtp),  Next: max_rcpt (smtp),  Prev: interface (smtp),  Up: The smtp transport

keepalive (smtp) _option_
-------------------------

Type: boolean
Default: true

This option controls the setting of SO_KEEPALIVE on outgoing socket
connections. This causes the kernel periodically to send some OOB
(out-of-band) data on idle connections. The option is provided for
symmetry with the global "smtp_accept_keepalive" option that has the
same effect on incoming SMTP connections.


File: exim.info,  Node: max_rcpt (smtp),  Next: multi_domain (smtp),  Prev: keepalive (smtp),  Up: The smtp transport

max_rcpt (smtp) _option_
------------------------

Type: integer
Default: 100

This option limits the number of RCPT commands that are sent in a single
SMTP message transaction. Each set of addresses is treated
independently, and so can cause parallel connections to the same host
if "remote_max_parallel" permits this.


File: exim.info,  Node: multi_domain (smtp),  Next: mx_domains (smtp),  Prev: max_rcpt (smtp),  Up: The smtp transport

multi_domain (smtp) _option_
----------------------------

Type: boolean
Default: true

When this option is set, the "smtp" transport can handle a number of
addresses containing a mixture of different domains provided they all
resolve to the same list of hosts. Turning the option off restricts the
transport to handling only one domain at a time. This is useful if you
want to use $domain in an expansion for the transport, because it is
set only when there is a single domain involved in a remote delivery.


File: exim.info,  Node: mx_domains (smtp),  Next: port (smtp),  Prev: multi_domain (smtp),  Up: The smtp transport

mx_domains (smtp) _option_
--------------------------

Type: domain list
Default: unset

If the "hosts" or "fallback_hosts" options are being used and names are
being looked up in the DNS, that is, the "gethostbyname" option is not
set, any domain name that matches this list is required to have an MX
record; an A record is not sufficient.


File: exim.info,  Node: port (smtp),  Next: protocol (smtp),  Prev: mx_domains (smtp),  Up: The smtp transport

port (smtp) _option_
--------------------

Type: string
Default: see below

This option specifies the TCP/IP port on the server to which Exim
connects. If it begins with a digit it is taken as a port number;
otherwise it is looked up using "getservbyname()". The default value is
normally `smtp', but if "protocol" is set to `lmtp', the default is
`lmtp'.


File: exim.info,  Node: protocol (smtp),  Next: retry_include_ip_address (smtp),  Prev: port (smtp),  Up: The smtp transport

protocol (smtp) _option_
------------------------

Type: string
Default: "smtp"

If this option is set to `lmtp' instead of `smtp', the default value
for the "port" option changes to `lmtp', and the transport operates the
LMTP protocol (RFC 2033) instead of SMTP. This protocol is sometimes
used for local deliveries into closed message stores. Exim also has
support for running LMTP over a pipe to a local process - see chapter
"The lmtp transport".


File: exim.info,  Node: retry_include_ip_address (smtp),  Next: serialize_hosts (smtp),  Prev: protocol (smtp),  Up: The smtp transport

retry_include_ip_address (smtp) _option_
----------------------------------------

Type: boolean
Default: true

Exim normally includes both the host name and the IP address in the key
it constructs for indexing retry data after a temporary delivery
failure. This means that when one of several IP addresses for a host is
failing, it gets tried periodically (controlled by the retry rules),
but use of the other IP addresses is not affected.

However, in some dialup environments hosts are assigned a different IP
address each time they connect. In this situation the use of the IP
address as part of the retry key leads to undesirable behaviour.
Setting this option false causes Exim to use only the host name. This
should normally be done on a separate instance of the "smtp" transport,
set up specially to handle the dialup hosts.


File: exim.info,  Node: serialize_hosts (smtp),  Next: service (smtp),  Prev: retry_include_ip_address (smtp),  Up: The smtp transport

serialize_hosts (smtp) _option_
-------------------------------

Type: host list
Default: unset

Because Exim operates in a distributed manner, if several messages for
the same host arrive at around the same time, more than one
simultaneous connection to the remote host can occur. This is not
usually a problem except when there is a slow link between the hosts.
In that situation it may be helpful to restrict Exim to one connection
at a time. This can be done by setting "serialize_hosts" to match the
relevant hosts.

Exim implements serialization by means of a hints database in which a
record is written whenever a process connects to one of the restricted
hosts, and deleted when the connection is completed. Obviously there is
scope for records to get left lying around if there is a system or
program crash. To guard against this, Exim ignores any records that are
more than six hours old.

However, if you set up any serialization, you should also arrange to
delete the hints database whenever your system reboots. The names of
the files all start with "serialize-<transport name>" and they are kept
in the "spool/db" directory. There may be one or two files per
serialized transport, depending on the type of DBM in use.


File: exim.info,  Node: service (smtp),  Next: size_addition (smtp),  Prev: serialize_hosts (smtp),  Up: The smtp transport

service (smtp) _option_
-----------------------

Type: string
Default: "smtp"

This option is a synonym for the "port" option.


File: exim.info,  Node: size_addition (smtp),  Next: tls_certificate (smtp),  Prev: service (smtp),  Up: The smtp transport

size_addition (smtp) _option_
-----------------------------

Type: integer
Default: 1024

If a remote SMTP server indicates that it supports the SIZE option of
the MAIL command, Exim uses this to pass over the message size at the
start of an SMTP transaction. It adds the value of "size_addition" to
the value it sends, to allow for headers and other text that may be
added during delivery by configuration options or in a transport
filter. It may be necessary to increase this if a lot of text is added
to messages.

Alternatively, if the value of "size_addition" is set negative, it
disables the use of the SIZE option altogether.


File: exim.info,  Node: tls_certificate (smtp),  Next: tls_privatekey (smtp),  Prev: size_addition (smtp),  Up: The smtp transport

tls_certificate (smtp) _option_
-------------------------------

Type: string, expanded
Default: unset

The value of this option is expanded, and must then be the absolute
path to a file which contains the client's certificate, for use when
sending a message over an encrypted connection. The values of $host and
$host_address are set to the name and address of the server during the
expansion. See chapter "Encrypted SMTP connections using TLS/SSL" for
details of TLS.


File: exim.info,  Node: tls_privatekey (smtp),  Next: tls_verify_certificates (smtp),  Prev: tls_certificate (smtp),  Up: The smtp transport

tls_privatekey (smtp) _option_
------------------------------

Type: string, expanded
Default: unset

The value of this option is expanded, and must then be the absolute
path to a file which contains the client's private key, for use when
sending a message over an encrypted connection. The values of $host and
$host_address are set to the name and address of the server during the
expansion. See chapter "Encrypted SMTP connections using TLS/SSL" for
details of TLS.


File: exim.info,  Node: tls_verify_certificates (smtp),  Next: tls_verify_ciphers (smtp),  Prev: tls_privatekey (smtp),  Up: The smtp transport

tls_verify_certificates (smtp) _option_
---------------------------------------

Type: string, expanded
Default: unset

The value of this option is expanded, and must then be the absolute
path to a file or a directory containing permitted server certificates,
for use when setting up an encrypted connection. The values of $host and
$host_address are set to the name and address of the server during the
expansion. See chapter "Encrypted SMTP connections using TLS/SSL" for
details of TLS.


File: exim.info,  Node: tls_verify_ciphers (smtp),  Prev: tls_verify_certificates (smtp),  Up: The smtp transport

tls_verify_ciphers (smtp) _option_
----------------------------------

Type: string, expanded
Default: unset

The value of this option is expanded, and must then be a list of
permitted ciphers, for use when setting up an encrypted connection. The
values of $host and $host_address are set to the name and address of
the server during the expansion. See chapter "Encrypted SMTP
connections using TLS/SSL" for details of TLS.


File: exim.info,  Node: Generic options common to both directors and routers,  Next: Additional generic options for directors,  Prev: The smtp transport,  Up: Top

Generic options common to both directors and routers
****************************************************

Directors and routers have sufficiently many generic options in common
to make it worth documenting them jointly in this chapter, to save
duplication. Any of these options can be used on any director or
router. Subsequent chapters describe the generic options that are
specific either to directors or to routers.



* Menu:

* condition (director or router)::
* debug_print (director or router)::
* domains (director or router)::
* driver (director or router)::
* errors_to (director or router)::
* fail_verify (director or router)::
* fail_verify_recipient (director or router)::
* fail_verify_sender (director or router)::
* fallback_hosts (director or router)::
* group (director or router)::
* headers_add (director or router)::
* headers_remove (director or router)::
* initgroups (director or router)::
* local_parts (director or router)::
* more (director or router)::
* require_files (director or router)::
* senders (director or router)::
* transport (director or router)::
* unseen (director or router)::
* user (director or router)::
* verify (director or router)::
* verify_only (director or router)::
* verify_recipient (director or router)::
* verify_sender (director or router)::
* Skipping directors and routers::


File: exim.info,  Node: condition (director or router),  Next: debug_print (director or router),  Prev: Generic options common to both directors and routers,  Up: Generic options common to both directors and routers

condition (director or router) _option_
---------------------------------------

Type: string, expanded
Default: unset

This option specifies a test that has to succeed for the driver to be
called.  The string is expanded, and if the result is a forced failure
or an empty string or one of the strings `0' or `no' or `false'
(checked without regard to the case of the letters), the driver is not
run, and the address is offered to the next one. This provides a means
of applying special-purpose conditions to the running of directors and
routers. The $home variable is available in the expansion for directors
that set it up. If the expansion fails, it causes Exim to panic. Some
of the other options below are common special cases that could in fact
be specified using "condition".


File: exim.info,  Node: debug_print (director or router),  Next: domains (director or router),  Prev: condition (director or router),  Up: Generic options common to both directors and routers

debug_print (director or router) _option_
-----------------------------------------

Type: string, expanded
Default: unset

If this option is set and debugging is enabled (see -d, -v, and
"debug_level"), the string is expanded and included in the debugging
output. This is to help with checking out the values of variables and
so on when debugging driver configurations. For example, if a
"condition" option appears not to be working, "debug_print" could be
used to output the variables it references. The output happens after
checks for "domains", "local_parts", "suffix" and "prefix", but before
checking "require_files" and "condition". A newline is added to the
text if it does not end with one.


File: exim.info,  Node: domains (director or router),  Next: driver (director or router),  Prev: debug_print (director or router),  Up: Generic options common to both directors and routers

domains (director or router) _option_
-------------------------------------

Type: domain list, expanded
Default: unset

If this option is set, the string is expanded, and is then interpreted
as a colon-separated list. Because of the expansion, if any of the
items contain backslash or dollar characters, they must be escaped with
a backslash. If the string is given in quotes, backslashes have to be
escaped a second time.  However, a special case is made for the string
`$key', which is commonly used in query-style lookups. Because such
lookups are individually re-expanded later, when they are used, the
string `$key' is passed unchanged through the initial overall expansion.

The driver is skipped unless the current domain matches the list. If
the match is achieved by means of a file lookup, the data that the
lookup returned for the domain is placed in the $domain_data variable
for use in string expansions of the driver's private options. For
directors, this option is the means by which a host can handle several
independent local domains. For routers, it can be used to reduce the
use of an expensive router such as "queryprogram" by doing a
preliminary plausibility check on the domain. Note that the current
domain may change as routing proceeds, as a router may replace the
original with a different one for subsequent routers to use.


File: exim.info,  Node: driver (director or router),  Next: errors_to (director or router),  Prev: domains (director or router),  Up: Generic options common to both directors and routers

driver (director or router) _option_
------------------------------------

Type: string
Default: unset

This option must always be set. It specifies which of the available
directors or routers is to be used.


File: exim.info,  Node: errors_to (director or router),  Next: fail_verify (director or router),  Prev: driver (director or router),  Up: Generic options common to both directors and routers

errors_to (director or router) _option_
---------------------------------------

Type: string, expanded
Default: unset

Delivery errors for any addresses handled or generated by the director
or router are sent to the address that results from expanding this
string, if it is set, and if it verifies as valid.  In other words,
this option sets the value of the envelope sender address to be used
for deliveries associated with the driver. If it is unset, or fails to
verify, the errors address associated with the incoming address
(normally the sender) is used. A typical use might be

     errors_to = aliasmaster

The "errors_to" setting associated with an address can be overridden if
it subsequently passes through other directors or routers that have
their own "errors_to" settings.


File: exim.info,  Node: fail_verify (director or router),  Next: fail_verify_recipient (director or router),  Prev: errors_to (director or router),  Up: Generic options common to both directors and routers

fail_verify (director or router) _option_
-----------------------------------------

Type: boolean
Default: false

Setting this option has the effect of setting both "fail_verify_sender"
and "fail_verify_recipient" to the same value.


File: exim.info,  Node: fail_verify_recipient (director or router),  Next: fail_verify_sender (director or router),  Prev: fail_verify (director or router),  Up: Generic options common to both directors and routers

fail_verify_recipient (director or router) _option_
---------------------------------------------------

Type: boolean
Default: false

If this option is true and an address is accepted by this driver when
verifying a recipient, verification fails. This option has no effect if
the "verify_recipient" option is false.


File: exim.info,  Node: fail_verify_sender (director or router),  Next: fallback_hosts (director or router),  Prev: fail_verify_recipient (director or router),  Up: Generic options common to both directors and routers

fail_verify_sender (director or router) _option_
------------------------------------------------

Type: boolean
Default: false

If this option is true and an address is accepted by this driver when
verifying a sender, verification fails. This option has no effect if the
"verify_sender" option is false.


File: exim.info,  Node: fallback_hosts (director or router),  Next: group (director or router),  Prev: fail_verify_sender (director or router),  Up: Generic options common to both directors and routers

fallback_hosts (director or router) _option_
--------------------------------------------

Type: string list
Default: unset

String expansion is not applied to this option. The argument must be a
colon-separated list of host names or IP addresses. If a driver queues
an address for a remote transport, this host list is associated with
the address, and used instead of the transport's fallback host list.
See the "fallback_hosts" option of the "smtp" transport for further
details.


File: exim.info,  Node: group (director or router),  Next: headers_add (director or router),  Prev: fallback_hosts (director or router),  Up: Generic options common to both directors and routers

group (director or router) _option_
-----------------------------------

Type: string
Default: see below

If a driver queues an address for a local transport, and the transport
does not specify a group, the group given here is used when running the
delivery process. If the string contains no $ characters, it is
resolved when Exim starts up. Otherwise, the string is expanded at the
time the director or router is run, and must yield either a digit
string or a name which can be looked up using "getgrnam()". For most
directors and routers the default is unset, but for the "forwardfile"
director with "check_local_user" set, and for the "localuser" director,
the default is taken from the "passwd" file. See also "initgroups" and
"user" and the discussion in chapter "Environment for running local
transports".


File: exim.info,  Node: headers_add (director or router),  Next: headers_remove (director or router),  Prev: group (director or router),  Up: Generic options common to both directors and routers

headers_add (director or router) _option_
-----------------------------------------

Type: string, expanded
Default: unset

This option specifies a string of text which is expanded at directing or
routing time, and associated with any addresses that are processed by
the driver. If the expanded string is empty, or if the expansion is
forced to fail, the option has no effect. Other expansion failures are
treated as configuration errors.

The expanded string must be in the form of one or more RFC 822 header
lines, separated by newlines (coded as `\n' inside a quoted string).
For example:

     headers_add = X-added-header: added by $primary_hostname

Exim does not check the syntax of these added headers, except that a
newline is supplied at the end if one is not present. If an address
passes through several directors and/or routers as a result of aliasing
or forwarding operations, any "headers_add" or "headers_remove"
specifications are cumulative. This does not apply for multiple
directors and/or routers that result from the use of `unseen'.

At transport time, for each address, all original headers listed in
"headers_remove" are removed, and those specified by "headers_add" are
added, in the order in which they were attached to the address. Then
any additional headers specified by the transport are added. It is not
possible to remove headers added to an address by "headers_add".

Addresses with different "headers_add" or "headers_remove" settings
cannot be batched.


File: exim.info,  Node: headers_remove (director or router),  Next: initgroups (director or router),  Prev: headers_add (director or router),  Up: Generic options common to both directors and routers

headers_remove (director or router) _option_
--------------------------------------------

Type: string, expanded
Default: unset

The string is expanded at directing or routing time and is then
associated with any addresses that are processed by the driver.  If the
expansion is forced to fail, the option has no effect. Other expansion
failures are treated as configuration errors.  After expansion, the
string must consist of a colon-separated list of header names, not
including the terminating colon, for example:

     headers_remove = return-receipt-to:acknowledge-to

It is used at transport time as described under "headers_add" above.


File: exim.info,  Node: initgroups (director or router),  Next: local_parts (director or router),  Prev: headers_remove (director or router),  Up: Generic options common to both directors and routers

initgroups (director or router) _option_
----------------------------------------

Type: boolean
Default: false

If the driver queues an address for a local transport, and this option
is true, and the uid supplied by the router or director is not
overridden by the transport, the "initgroups()" function is called when
running the transport to ensure that any additional groups associated
with the uid are set up. See also "group" and "user" and the discussion
in chapter "Environment for running local transports".


File: exim.info,  Node: local_parts (director or router),  Next: more (director or router),  Prev: initgroups (director or router),  Up: Generic options common to both directors and routers

local_parts (director or router) _option_
-----------------------------------------

Type: string list, expanded
Default: unset

If this option is set, the string is expanded, and is then interpreted
as a colon-separated list. Because of the expansion, if any of the
items contain backslash or dollar characters, they must be escaped with
a backslash.  However, a special case is made for the string `$key',
which is commonly used in query-style lookups. Because such lookups are
individually re-expanded later, when they are used, the string `$key'
is passed unchanged through the initial overall expansion.

The driver is run only if the local part of the address matches the
list, which is tested in the same way as a domain list and which may
therefore include plain file names, file lookups, and negation. Because
the string is expanded, it is possible to make it depend on the domain,
for example:

     local_parts = dbm;/usr/local/specials/$domain

If the match is achieved by a lookup, the data that the lookup returned
for the local part is placed in the variable $local_part_data for use in
expansions of the driver's private options. You might use this option,
for example, if you have a large number of local virtual domains, and
you want to send all postmaster mail to the same place without having
to set up an alias in each virtual domain:

     postmaster:
       local_parts = postmaster
       driver = smartuser
       new_address = postmaster@real.dom.ain


File: exim.info,  Node: more (director or router),  Next: require_files (director or router),  Prev: local_parts (director or router),  Up: Generic options common to both directors and routers

more (director or router) _option_
----------------------------------

Type: boolean
Default: true

If this option is false, and the driver declines to handle an address,
no further drivers are tried, and directing or routing fails. This
applies even in the case of address verification where the driver was
not run because the "verify" option was off (see section "Skipping
directors and routers").  However, if a router explicitly passes an
address to the following router by means of the setting

     self = pass

or by some other means, the setting of "more" is ignored.


File: exim.info,  Node: require_files (director or router),  Next: senders (director or router),  Prev: more (director or router),  Up: Generic options common to both directors and routers

require_files (director or router) _option_
-------------------------------------------

Type: string list, expanded
Default: unset

The value of this option is first expanded and then interpreted as a
colon-separated list of strings. If the option is used on a "localuser"
director, or on a "forwardfile" director that has either of the
"check_local_user" or "file_directory" options set, the expansion
variable $home may appear in the list, referring to the home directory
of the user whose name is that of the local part of the address.

If any string is empty, it is ignored. Otherwise, except as described
below, each string must be a fully qualified file path, optionally
preceded by `!'.  The paths are passed to the "stat()" function to test
for the existence of the files or directories. The driver is skipped if
any paths not preceded by `!' do not exist, or if any paths preceded by
`!' do exist.

The "stat()" function is normally run under the exim uid (or root if
such is not defined). During the delivery of a message, it is possible
to arrange for this test to be run under a specific uid and gid (which
is set by means of "seteuid()" and "setegid()").

Warning: Unfortunately, this is not possible when the driver is being
run to verify addresses for an incoming SMTP message, because at that
time, Exim has given up its root privilege. Therefore, this facility is
useful only if you can set "no_verify" on drivers that use it.

If an item in a "require_files" list does not contain any forward slash
characters, it is taken to be the user (and optional group, separated
by a comma) to be used for testing subsequent files in the list. If no
group is specified but the user is specified symbolically, the gid
associated with the uid is used; otherwise the gid is not changed. For
example:

     require_files = mail:/some/file
     require_files = ${local_part}:${home}/.procmailrc

The second example works because the "require_files" string is expanded
before use.  If a user or group name in a "require_files" list does not
exist, the "require_files" condition fails.

If "stat()" cannot determine whether a file exists or not, delivery of
the message is deferred. This can happen when NFS-mounted filesystems
are unavailable.

Sometimes "stat()" yields the error EACCES (`Permission denied'). This
means that the user is not permitted to read one of the directories on
the file's path. The default action is to consider this a configuration
error, and delivery is deferred because the existence or non-existence
of the file cannot be determined. However, in some circumstances it may
be desirable to treat this condition as if the file did not exist. If
the file name (or the exclamation mark that precedes the file name for
non-existence) is preceded by a plus sign, then the EACCES error is
treated as if the file did not exist.  For example:

     require_files = +/some/file

This option provides a general mechanism for predicating the running of
a director or router on the existence or non-existence of certain files
or directories. A failure to expand the string, or the presence of a
path within it that is not fully qualified causes a panic error.  This
includes forced failure, because the whole string is expanded once,
before being interpreted as a list. If you want a particular variant of
the expansion to specify that no files are to be checked, you should
cause it to yield an empty string rather than forcing failure.


File: exim.info,  Node: senders (director or router),  Next: transport (director or router),  Prev: require_files (director or router),  Up: Generic options common to both directors and routers

senders (director or router) _option_
-------------------------------------

Type: address list, expanded
Default: unset

The value of this option is expanded, and the result of the expansion
must be a colon-separated address list, in the same format as used for
general options like "sender_reject". The driver is run only if the
sender address matches something in the "senders" list (when it is set).
Using this option on a director makes it possible to implement closed
mailing lists (see chapter "Using Exim to handle mailing lists").

There are issues concerning verification when the running of directors
or routers is dependent on the sender. When Exim is verifying an
"errors_to" setting in either "forwardfile" or "aliasfile", it sets the
sender to the null string. If using the -bt option to check a
configuration file, it is necessary also to use the -f option to set an
appropriate sender. For incoming mail, the sender is unset when
verifying the sender, but is available when verifying any recipients.
If the SMTP VRFY command is enabled, it must be used after MAIL if the
sender address matters.


File: exim.info,  Node: transport (director or router),  Next: unseen (director or router),  Prev: senders (director or router),  Up: Generic options common to both directors and routers

transport (director or router) _option_
---------------------------------------

Type: string, expanded
Default: unset

Some directors and routers require a transport to be supplied, except
when "verify_only" is set, where it is not relevant. Others require
that a transport not be supplied, and for some it is optional. The
string must be the name of a configured transport instance, or an
expandable string, thus allowing transports to be dynamically selected.
At directing or routing time, when a driver decides to accept an
address, the string is expanded, and must yield the name of an
available transport. If it does not, delivery is deferred. This isn't
as safe as fixed transports, whose existence is checked at
initialization time.


File: exim.info,  Node: unseen (director or router),  Next: user (director or router),  Prev: transport (director or router),  Up: Generic options common to both directors and routers

unseen (director or router) _option_
------------------------------------

Type: boolean
Default: false

Setting this option has a similar effect to the "unseen" command
qualifier in filter files.  It causes a copy of the incoming address to
be passed on to subsequent drivers, when the current one succeeds in
handling it. It can be used to cause copies of messages to be delivered
elsewhere. The effect is to clone the address before processing one
copy of it, so options such as "headers_add" on the current director do
not affect the other copy.


File: exim.info,  Node: user (director or router),  Next: verify (director or router),  Prev: unseen (director or router),  Up: Generic options common to both directors and routers

user (director or router) _option_
----------------------------------

Type: string
Default: see below

If the driver queues an address for a local transport, and the
transport does not specify a user, the user given here is used when
running the delivery process. If the string contains no $ characters,
it is resolved when Exim starts up. Otherwise, the string is expanded
at the time the director or router is run, and must yield either a
digit string or a name which can be looked up using "getpwnam()". In
the latter case, the group associated with the user is used as a
default for the "group" option.

For most directors and routers the default for "user" is unset, but for
the "forwardfile" director with "check_local_user" set, and for the
"localuser" director, the default is taken from the "passwd" file. See
also "initgroups" and "group" and the discussion in chapter
"Environment for running local transports".


File: exim.info,  Node: verify (director or router),  Next: verify_only (director or router),  Prev: user (director or router),  Up: Generic options common to both directors and routers

verify (director or router) _option_
------------------------------------

Type: boolean
Default: true

Setting this option has the effect of setting "verify_sender" and
"verify_recipient" to the same value.


File: exim.info,  Node: verify_only (director or router),  Next: verify_recipient (director or router),  Prev: verify (director or router),  Up: Generic options common to both directors and routers

verify_only (director or router) _option_
-----------------------------------------

Type: boolean
Default: false

If this option is set, the driver is used only when verifying an
address or testing with the -bv option, not when actually doing a
delivery, testing with the -bt option, or running the SMTP EXPN command
(see the "expn" generic option for directors). It can be further
restricted to verifying only senders or recipients by means of
"verify_sender" and "verify_recipient".


File: exim.info,  Node: verify_recipient (director or router),  Next: verify_sender (director or router),  Prev: verify_only (director or router),  Up: Generic options common to both directors and routers

verify_recipient (director or router) _option_
----------------------------------------------

Type: boolean
Default: true

If this option is false, this driver is skipped when verifying recipient
addresses. It is usual to set it false for instances of the "smartuser"
director that have no other conditions imposed on the address.


File: exim.info,  Node: verify_sender (director or router),  Next: Skipping directors and routers,  Prev: verify_recipient (director or router),  Up: Generic options common to both directors and routers

verify_sender (director or router) _option_
-------------------------------------------

Type: boolean
Default: true

If this option is false, this driver is skipped when verifying sender
addresses. It is usual to set it false for instances of the "smartuser"
director that have no other conditions imposed on the address.


File: exim.info,  Node: Skipping directors and routers,  Prev: verify_sender (director or router),  Up: Generic options common to both directors and routers

Skipping directors and routers
==============================

A number of the generic options that are common to directors and
routers are concerned with controlling which drivers are run in
particular circumstances.  They interact with each other in the
following way:

If the domain and local part of an address are not in agreement with
"domains" and "local_parts" (when set), or if the "condition" option
fails, or if verification is happening and the "verify_sender" or
"verify_recipient" option (as appropriate) is turned off, or if
"verify_only" is set and verification is not happening, the director or
router is skipped and the next one is tried.

Otherwise, if the "more" option is false, no subsequent drivers are ever
called, except when a router explicitly passes an address that routes
to the local host on to the following driver, by means of the generic
"self" option or the "host_find_failed" option of the "domainlist"
router. The current driver is itself called unless

   * The existence or non-existence of files listed in the
     "require_files" option is not as expected, or

   * The sender of the message is not in agreement with "senders".

Both the "senders" and "condition" tests are done after checking for
file existence, so that they can contain references to files whose
existence is tested. The order of testing the options which are
expanded strings is: "domains", "local_parts", "require_files",
"senders", "condition". When any test fails, no further expansions are
done.

In the case of directors, there are some additional conditions that are
tested here (see section "Skipping directors" in chapter "Additional
generic options for directors").

The "unseen" option causes directing or routing to continue when it
would otherwise cease. This is the complementary action to "no_more",
which causes it to cease when it would otherwise continue.

The "verify", "fail_verify", and "verify_only" options make it possible
to separate those addresses which correspond to a real delivery from
those which are recognized, but which do something else if actually
encountered in a message.

For example, a "smartuser" director might be used to pass all
unrecognized local parts to a script that tries to generate a helpful
error message, or to a different machine that might be able to handle
them. This means that no local part will ever cause a directing
failure. However, if (for example) verification of senders is taking
place (the "sender_verify" main configuration option), you probably
don't want <random-local-part@your.domain> to be accepted. The solution
is to set "no_verify" or "no_verify_sender" on the "smartuser" director.

On our systems in Cambridge we can identify users whose accounts have
recently been cancelled, and their mail is piped to a script which
sends back a more helpful message than `user unknown'. Verification of
such local parts as senders should fail, but just setting "no_verify"
on the director doesn't work, because the local part is then passed to
a "localuser" director that may still find it in the password file.
(Initially, cancellation just resets the password.) This is the sort of
case for which "fail_verify" was invented. It makes it possible to fail
a set of local parts that is defined by what a specific director
matches.


File: exim.info,  Node: Additional generic options for directors,  Next: Options common to the aliasfile and forwardfile directors,  Prev: Generic options common to both directors and routers,  Up: Top

Additional generic options for directors
****************************************

The following additional generic options apply to all directors, in
addition to the generic options common to both directors and routers
which are described in chapter "Generic options common to both
directors and routers". Directors are concerned with addresses whose
domains match something in "local_domains", or which have been
explicitly determined to be local by a router.



* Menu:

* current_directory (director)::
* expn (director)::
* home_directory (director)::
* new_director (director)::
* prefix (director)::
* prefix_optional (director)::
* suffix (director)::
* suffix_optional (director)::
* Skipping directors::


File: exim.info,  Node: current_directory (director),  Next: expn (director),  Prev: Additional generic options for directors,  Up: Additional generic options for directors

current_directory (director) _option_
-------------------------------------

Type: string, expanded
Default: unset

This option associates a current directory with any address that a
director directs to a local transport. This can happen either because a
transport is explicitly configured for the director, or because it
generates a delivery to a file or a pipe. During the delivery process
(that is, at transport time), this option string is expanded and is set
as the current directory, unless overridden by a setting on the
transport. See chapter "Environment for running local transports" for
details of the local delivery environment. The "forwardfile" director
handles this option in a special way (see section "Special treatment of
home_directory and current_directory" in chapter "The forwardfile
director").


File: exim.info,  Node: expn (director),  Next: home_directory (director),  Prev: current_directory (director),  Up: Additional generic options for directors

expn (director) _option_
------------------------

Type: boolean
Default: true

If this option is turned off, the director is skipped when testing an
address as a result of processing an SMTP EXPN command. You might, for
example, want to turn it off on a director for users' `.forward' files,
while leaving it on for the system alias file. The use of the SMTP EXPN
command is permitted only from hosts that match the "smtp_expn_hosts"
main configuration option.

This option is specific to directors because EXPN applies only to local
addresses, so no address that is an argument to EXPN is ever passed to
any router. When Exim is running an EXPN command, it is similar to
testing an address with -bt. Compare VRFY, whose counterpart is -bv.


File: exim.info,  Node: home_directory (director),  Next: new_director (director),  Prev: expn (director),  Up: Additional generic options for directors

home_directory (director) _option_
----------------------------------

Type: string, expanded
Default: unset

This option associates a home directory with any address that a director
directs to a local transport. This can happen either because a
transport is explicitly configured for the director, or because it
generates a delivery to a file or a pipe. During the delivery process
(that is, at transport time), the option string is expanded and is set
as the home directory, unless overridden by a setting on the transport.
This means that the expansion variable $home does not take on this
value at directing time. In particular, it cannot be used in the
"require_files" option. See chapter "Environment for running local
transports" for details of the local delivery environment. The
"forwardfile" and "localuser" directors handle this option in a special
way (see section "Special treatment of home_directory and
current_directory" in chapter "The forwardfile director").


File: exim.info,  Node: new_director (director),  Next: prefix (director),  Prev: home_directory (director),  Up: Additional generic options for directors

new_director (director) _option_
--------------------------------

Type: string
Default: unset

Sometimes an administrator knows that it is pointless to reprocess
addresses generated from alias or forward files with the same director
again. For example, if an alias file translates real names into login
ids there is no point searching the alias file again, especially if it
is a large file.

The "new_director" option can be set to the name of any director
instance. It causes the directing of any generated local addresses to
start at the named director instead of the first director. The named
director can be any configured director. This option has no effect if
the director in which it is set does not generate new addresses, or if
such addresses are not in local domains.


File: exim.info,  Node: prefix (director),  Next: prefix_optional (director),  Prev: new_director (director),  Up: Additional generic options for directors

prefix (director) _option_
--------------------------

Type: string list
Default: unset

If this option is set, the director is skipped unless the local part
starts with one of the given strings, or the "prefix_optional" option
is true.  The list is scanned from left to right, and the first prefix
that matches is used.  A limited form of wildcard is available; if the
prefix begins with an asterisk, it matches the longest possible
sequence of arbitrary characters at the start of the local part. An
asterisk should therefore always be followed by some character that
does not occur in normal local parts.  Wildcarding can be used to set
up multiple user mailboxes, as described in chapter "Multiple user
mailboxes".

While the director is running, the prefix is removed from the local
part, and is available in the expansion variable "local_part_prefix".
If the director succeeds, this remains true during subsequent delivery.

The prefix facility is commonly used to handle local parts of the form
"owner-something". Another common use is to support local parts of the
form "real-username" to bypass a user's `.forward' file - helpful when
trying to tell a user their forwarding is broken - by placing a
director like this one immediately before the director that handles
`.forward' files:

     real_localuser:
       driver = localuser
       transport = local_delivery
       prefix = real-

If both "prefix" and "suffix" are set for a director, both conditions
must be met if not optional. Care must be taken if wildcards are used
in both a prefix and a suffix on the same director. Different separator
characters must be used to avoid ambiguity.


File: exim.info,  Node: prefix_optional (director),  Next: suffix (director),  Prev: prefix (director),  Up: Additional generic options for directors

prefix_optional (director) _option_
-----------------------------------

Type: boolean
Default: false

See "prefix" above.


File: exim.info,  Node: suffix (director),  Next: suffix_optional (director),  Prev: prefix_optional (director),  Up: Additional generic options for directors

suffix (director) _option_
--------------------------

Type: string list
Default: unset

This option operates in the same way as "prefix", except that the local
part must end (rather than start) with the given string, the
"suffix_optional" option determines whether the suffix is mandatory,
and the wildcard * character, if present, must be the last character of
the suffix. This option facility is commonly used to handle local parts
of the form "something-request" and multiple user mailboxes of the form
"username-foo".


File: exim.info,  Node: suffix_optional (director),  Next: Skipping directors,  Prev: suffix (director),  Up: Additional generic options for directors

suffix_optional (director) _option_
-----------------------------------

Type: boolean
Default: false

See "suffix" above.


File: exim.info,  Node: Skipping directors,  Prev: suffix_optional (director),  Up: Additional generic options for directors

Skipping directors
==================

Section "Skipping directors and routers" in chapter "Generic options
common to both directors and routers" above describes the circumstances
in which the generic options that are common to both directors and
routers cause a driver to be skipped. Directors have additional generic
options which impose some further condition.

The "new_director" generic option causes the directing of a generated
local address to start at a particular director, thus skipping those
above it for that address.

Processing of the "prefix" and "suffix" options does not happen until
after the check of "local_parts" is done, so the local part that is
checked at that stage is the full local part. If you want to select a
director based on a partial local part, you can use a regular
expression, or make use of the "condition" option to do more complicated
processing (such as looking up a prefix-stripped local part in a file).

The following additional conditions, which are applied after the
initial checks on the domain etc., prevent the current director from
being run:

   * An SMTP EXPN command is being processed and the director's "expn"
     option is turned off, or

   * There is a prefix or suffix mismatch, or

   * The address was generated by aliasing or forwarding and is
     identical to an ancestor address that was processed by this
     director. This restriction breaks addressing loops.


File: exim.info,  Node: Options common to the aliasfile and forwardfile directors,  Next: The aliasfile director,  Prev: Additional generic options for directors,  Up: Top

Options common to the aliasfile and forwardfile directors
*********************************************************

The "aliasfile" and "forwardfile" directors have a lot in common. Each
of them generates a list of new destinations from an incoming address;
the main difference is in the way the list is obtained. As Exim has
developed, they have grown more and more similar, and one day they may
merge into a single director.  There are a substantial number of
private options that are identical in both these directors, so in order
to avoid too much duplication, these common options are described
separately in this chapter.



* Menu:

* check_ancestor::
* directory_transport::
* directory2_transport::
* file_transport::
* forbid_file::
* forbid_include::
* forbid_pipe::
* freeze_missing_include::
* hide_child_in_errmsg::
* modemask::
* one_time::
* owners::
* owngroups::
* pipe_transport::
* qualify_preserve_domain::
* rewrite::
* skip_syntax_errors::
* syntax_errors_text::
* syntax_errors_to::


File: exim.info,  Node: check_ancestor,  Next: directory_transport,  Prev: Options common to the aliasfile and forwardfile directors,  Up: Options common to the aliasfile and forwardfile directors

check_ancestor _option_
-----------------------

Type: boolean
Default: false

This option is concerned with handling generated addresses which are
the same as some address in the list of aliasing or forwarding
ancestors of the current address. Although it is turned off by default
in the code, it is set in the default configuration file for handling
users' `.forward' files. It is recommended for this use of the
"forwardfile" director, but is not commonly set for "aliasfile".

When "check_ancestor" is set, if a generated address is the same as any
ancestor of the current address, it is not used, but instead a copy of
the current address is passed on to subsequent directors. This helps in
the case where local part A is aliased to B, and B has a `.forward'
file pointing back to A. For example: `Joe.Bloggs' is aliased to `jb'
and "~jb/.forward" contains:

     \Joe.Bloggs, <other item(s)>

Without the "check_ancestor" setting, either local part (`jb' or
`joe.bloggs') gets processed once by each director and so ends up as it
was originally. If `jb' is the real mailbox name, mail to `jb' gets
delivered (having been turned into `joe.bloggs' by the `.forward' file
and back to `jb' by the alias), but mail to `joe.bloggs' fails. Setting
"check_ancestor" on the "forwardfile" director prevents it from turning
`jb' back into `joe.bloggs' when that was the original address.


File: exim.info,  Node: directory_transport,  Next: directory2_transport,  Prev: check_ancestor,  Up: Options common to the aliasfile and forwardfile directors

directory_transport _option_
----------------------------

Type: string, expanded
Default: unset

An "aliasfile" or "forwardfile" director sets up a direct delivery to a
directory when a path name ending with a slash is specified as a new
`address'.  The transport used is specified by this option, which,
after expansion, must be the name of a configured transport.


File: exim.info,  Node: directory2_transport,  Next: file_transport,  Prev: directory_transport,  Up: Options common to the aliasfile and forwardfile directors

directory2_transport _option_
-----------------------------

Type: string, expanded
Default: unset

An "aliasfile" or "forwardfile" director sets up an alternative direct
delivery to a directory when a path name ending with two slashes is
specified as a new `address'. The transport used is specified by this
option, which, after expansion, must be the name of a configured
transport.


File: exim.info,  Node: file_transport,  Next: forbid_file,  Prev: directory2_transport,  Up: Options common to the aliasfile and forwardfile directors

file_transport _option_
-----------------------

Type: string, expanded
Default: unset

An "aliasfile" or "forwardfile" director sets up a direct delivery to a
file when a path name not ending in a slash is specified as a new
`address'. The transport used is specified by this option, which, after
expansion, must be the name of a configured transport.


File: exim.info,  Node: forbid_file,  Next: forbid_include,  Prev: file_transport,  Up: Options common to the aliasfile and forwardfile directors

forbid_file _option_
--------------------

Type: boolean
Default: false

If this option is true, this director may not generate a new address
which specifies delivery to a local file or directory. If it attempts
to do so, a delivery failure occurs.


File: exim.info,  Node: forbid_include,  Next: forbid_pipe,  Prev: forbid_file,  Up: Options common to the aliasfile and forwardfile directors

forbid_include _option_
-----------------------

Type: boolean
Default: false

If this option is true, items of the form

     :include:<path name>

are not permitted in alias or forward files, and if one is encountered,
the message is frozen.


File: exim.info,  Node: forbid_pipe,  Next: freeze_missing_include,  Prev: forbid_include,  Up: Options common to the aliasfile and forwardfile directors

forbid_pipe _option_
--------------------

Type: boolean
Default: false

If this option is true, this director may not generate a new address
which specifies delivery to a pipe. If it attempts to do so, a delivery
failure occurs.


File: exim.info,  Node: freeze_missing_include,  Next: hide_child_in_errmsg,  Prev: forbid_pipe,  Up: Options common to the aliasfile and forwardfile directors

freeze_missing_include _option_
-------------------------------

Type: boolean
Default: true

If a file named by the `include' mechanism fails to open, delivery is
frozen if this option is true. Otherwise, delivery is just deferred.
Unsetting this option can be useful if included files are NFS mounted
and may not always be available.


File: exim.info,  Node: hide_child_in_errmsg,  Next: modemask,  Prev: freeze_missing_include,  Up: Options common to the aliasfile and forwardfile directors

hide_child_in_errmsg _option_
-----------------------------

Type: boolean
Default: false

If this option is set true, it prevents Exim from quoting a child
address if it generates a bounce or delay message for it. Instead it
says `an address generated from <the top level address>'. Of course,
this applies only to bounces generated locally. If a message is
forwarded to another host, its bounce may well quote the generated
address.


File: exim.info,  Node: modemask,  Next: one_time,  Prev: hide_child_in_errmsg,  Up: Options common to the aliasfile and forwardfile directors

modemask _option_
-----------------

Type: octal integer
Default: 022

This specifies mode bits which must not be set for a forward file, or
for an alias file which is an actual file. It does not apply when
aliases are being looked up using a database query. If any of the
forbidden bits is set, delivery is deferred.


File: exim.info,  Node: one_time,  Next: owners,  Prev: modemask,  Up: Options common to the aliasfile and forwardfile directors

one_time _option_
-----------------

Type: boolean
Default: false

Sometimes the fact that Exim re-evaluates aliases and reprocesses
forward files each time it tries to deliver a message causes problems.
This is particularly true in the case of mailing lists and so is more
likely to be a problem with forward files than with alias files.

If "one_time" is set and any addresses generated by the director fail to
deliver at the first attempt, the failing addresses are added to the
message as `top level' addresses, and the parent address that generated
them is marked `delivered'. Thus, aliasing or forwarding does not
happen again at the next delivery attempt.  Warning: This means that
any header line addition or removal that is specified by this director
will be lost if delivery does not succeed at the first attempt.

To ensure that the director generates only addresses (as opposed to
pipe or file deliveries or auto-replies) "forbid_file" and
"forbid_pipe" must also be set, and for "forwardfile" with "filter"
set, "forbid_reply" must also be set.

The original top-level address is remembered with each of the generated
addresses, and is output in any log messages. However, any intermediate
parent addresses are not recorded. This makes a difference to the log
only if "log_all_parents" is set. It is expected that "one_time" will
typically be used for mailing lists, where there is normally just one
level of expansion.


File: exim.info,  Node: owners,  Next: owngroups,  Prev: one_time,  Up: Options common to the aliasfile and forwardfile directors

owners _option_
---------------

Type: string list
Default: unset

This specifies a list of permitted owners for a forward file, or for an
alias file which is an actual file. It does not apply when aliases are
being looked up using a database query. In the case of "forwardfile",
this list is in addition to the local user when "check_local_user" is
set. If "owners" is unset (and "check_local_user" is false for
"forwardfile"), no check on the ownership is done. If the file is not
correctly owned, delivery is deferred and the message is frozen.


File: exim.info,  Node: owngroups,  Next: pipe_transport,  Prev: owners,  Up: Options common to the aliasfile and forwardfile directors

owngroups _option_
------------------

Type: string list
Default: unset

This specifies a list of permitted groups for a forward file, or for an
alias file which is an actual file. It does not apply when aliases are
being looked up using a database query. In the case of "forwardfile",
the list is addition to the local user's group in the case when
"check_local_user" is set.  However, group ownership of forward files
is checked only when "check_group" (an option private to "forwardfile")
is set. If "owngroups" is unset, no check on the file's group is done.
If the file's group is incorrect, the delivery is deferred and the
message is frozen.


File: exim.info,  Node: pipe_transport,  Next: qualify_preserve_domain,  Prev: owngroups,  Up: Options common to the aliasfile and forwardfile directors

pipe_transport _option_
-----------------------

Type: string, expanded
Default: unset

An "aliasfile" or "forwardfile" director sets up a direct delivery to a
pipe when a string starting with a vertical bar character is specified
as a new `address'. The transport used is specified by this option,
which, after expansion, must be the name of a configured transport.


File: exim.info,  Node: qualify_preserve_domain,  Next: rewrite,  Prev: pipe_transport,  Up: Options common to the aliasfile and forwardfile directors

qualify_preserve_domain _option_
--------------------------------

Type: boolean
Default: false

If this is set and an unqualified address (one without a domain) is
generated, it is qualified with the domain of the incoming address
instead of the global setting in "qualify_recipient".


File: exim.info,  Node: rewrite,  Next: skip_syntax_errors,  Prev: qualify_preserve_domain,  Up: Options common to the aliasfile and forwardfile directors

rewrite _option_
----------------

Type: boolean
Default: true

If this option is set false, addresses generated by the director are not
subject to address rewriting. Otherwise, they are treated like new
addresses.


File: exim.info,  Node: skip_syntax_errors,  Next: syntax_errors_text,  Prev: rewrite,  Up: Options common to the aliasfile and forwardfile directors

skip_syntax_errors _option_
---------------------------

Type: boolean
Default: false

If "skip_syntax_errors" is set, a malformed address in an alias list or
a non-filter forward file that causes a parsing error is skipped, and
an entry is written to the main log. This may be useful for mailing
lists that are automatically managed, but note the inherent danger.

For "aliasfile", Exim always considers it to be an error if no
addresses at all are generated, even if this option is set. However,
for "forwardfile", if all the addresses in the list are malformed, the
original address is passed on to subsequent directors.

If "skip_syntax_errors" is set for an Exim filter file, any syntax
error in the filter file causes filtering to be abandoned, the incident
is logged, and the address is passed on to the next director.


File: exim.info,  Node: syntax_errors_text,  Next: syntax_errors_to,  Prev: skip_syntax_errors,  Up: Options common to the aliasfile and forwardfile directors

syntax_errors_text _option_
---------------------------

Type: string, expanded
Default: unset

See "syntax_errors_to".


File: exim.info,  Node: syntax_errors_to,  Prev: syntax_errors_text,  Up: Options common to the aliasfile and forwardfile directors

syntax_errors_to _option_
-------------------------

Type: string
Default: unset

This option applies only when "skip_syntax_errors" is set. If any
addresses are skipped because of syntax errors, a mail message is sent
to the address specified by "syntax_errors_to", giving details of the
failing address(es).  If "syntax_errors_text" is set, its contents are
expanded and placed at the head of the error message. Often it will be
appropriate to set "syntax_errors_to" to be the same address as the
generic "errors_to" option.


File: exim.info,  Node: The aliasfile director,  Next: The forwardfile director,  Prev: Options common to the aliasfile and forwardfile directors,  Up: Top

The aliasfile director
**********************

The "aliasfile" director expands local parts by consulting a file or
database of aliases. An incoming local part is looked up, and the
result is a list of one or more replacement addresses, file names, pipe
commands or certain special items. The expansion may safely contain the
same local part as the input as one of its items, because a director is
automatically skipped if it has an identical ancestor that was
processed by that director. For the case of a new alias address that is
identical to the input address, this rule means in effect that it
starts its processing at the following director.

The alias list can be obtained from a text file that is searched
linearly, a DBM direct-access file, a NIS or NIS+ map, an LDAP
database, or any other kind of lookup supported by Exim (see chapter
"File and database lookups").

Unless the "locally_caseless" option has been set false, local parts are
forced to lower case, and so the keys in alias files should normally be
in lower case. For linearly searched files this isn't in fact
necessary, because the searching is done in a case-independent manner,
but it is relevant for other forms of alias lookup. The "exim_dbmbuild"
utility can be used to convert a text file into a DBM database; the
keys are lower-cased by default.



* Menu:

* Specifying a transport for aliasfile::
* Alias file format::
* Types of alias item::
* Duplicate addresses::
* Repeated alias expansion::
* Errors in alias files::
* Aliasfile private options::


File: exim.info,  Node: Specifying a transport for aliasfile,  Next: Alias file format,  Prev: The aliasfile director,  Up: The aliasfile director

Specifying a transport for aliasfile
====================================

The generic "transport" option must not be specified for "aliasfile"
when it is fulfilling a traditional aliasing function. If "transport"
is specified, the director behaves differently, and doesn't really
`alias' at all. Its lookup facilities are used as a means of validating
the incoming address, but if it is successful, the message is directed
to the given transport while retaining the original address. The data
that is returned from the lookup is not used. For example, a file
containing a list of cancelled users can be used to direct messages
addressed to them to a particular script.

Another common use of "aliasfile" with a transport is for handling local
deliveries without reference to "/etc/passwd". Local parts are
validated by using "aliasfile" to look them up in a file or database,
which can also be used to hold information for use during delivery (for
example, the uid to use, or the location of the mailbox). There is a
sample configuration that gives more detail.


File: exim.info,  Node: Alias file format,  Next: Types of alias item,  Prev: Specifying a transport for aliasfile,  Up: The aliasfile director

Alias file format
=================

A textual alias file to be searched linearly consists of entries that
start with the alias name, terminated by a colon or white space.
However, a colon must be used if data for the alias starts with a
colon, because white space is permitted between the alias name and its
terminating colon. This is Exim's standard "lsearch" format (see
chapter "File and database lookups").

The remainder of the entry, up to the end of the line, consists of a
list of addresses, file names, pipe commands, or certain special items
(see below). The items in the list are separated by commas. The list
can be continued over several lines by starting each of the
continuation lines with white space.  A single space is retained at
each junction. However, a comma is still required following an item
that ends at the end of a line, because the "lsearch" lookup code
removes newlines from the string it returns.

Lines in textual alias files that start with a # character are
comments, and are ignored, and a # may also appear following a comma in
an item list, in which case everything after the # is ignored. Other
forms of alias file (DBM, NIS, LDAP, etc.) involve lookups using the
local part as a key on files and databases. The value returned is a
list of items separated by commas or newlines. The returned list is
normally used exactly as it stands, but if the "expand" option is set,
it is first passed through the string expansion mechanism.

By default, alias names are simple local parts such as `postmaster',
but if the "include_domain" option is set, they must contain both a
local part and a domain, thus allowing aliases for more than one domain
to be held in a single file.

It is possible to set up a default in an alias file that uses a
single-key lookup type. This matches incoming local parts that do not
match any other entry when the lookup type name is followed by an
asterisk, for example "dbm*" (see section "Default values in single-key
lookups" in chapter "File and database lookups"). For query-style
lookups, the "queries" option specifies a list of queries to be tried.


File: exim.info,  Node: Types of alias item,  Next: Duplicate addresses,  Prev: Alias file format,  Up: The aliasfile director

Types of alias item
===================

If an item is entirely enclosed in double quotes, these are removed.
Otherwise double quotes are retained because some forms of mail address
require their use (but never to enclose the entire address). In the
following description, `item' refers to what remains after any
surrounding double quotes have been removed. An item may safely be the
same as the local part currently under consideration, because any
director is automatically skipped if any ancestor has the same local
part and was processed by that director.

   * If an item begins with `\' and the rest of the item parses as a
     valid RFC 822 address that does not include a domain, the item is
     qualified using the domain of the incoming address. The use of `\'
     makes a difference only if there is more than one local domain. In
     the absence of a leading `\', unqualified addresses are qualified
     using the value in "qualify_recipient", unless
     "qualify_preserve_domain" is set.  It is not necessary to include
     `\' in aliases to prevent directing loops, because Exim has its
     own method of loop detection.

   * An item is treated as a pipe command if it begins with `|' and
     does not parse as a valid RFC 822 address that includes a domain.
     A transport for running the command must be specified by the
     "pipe_transport" option. Either the director or the transport must
     specify a user and group under which to run the delivery.

     Either single or double quotes can be used for enclosing the
     individual arguments of the pipe command; no interpretation of
     escapes is done for single quotes. If the command contains a comma
     character, it is necessary to put the whole item in double quotes,
     for example:

          "|/some/command ready,steady,go"

     since items are terminated by commas. Do not, however, quote just
     the command.  An item such as

          |"/some/command ready,steady,go"

     is interpreted as a pipe with a rather strange command name, and
     no arguments.

   * An item is interpreted as a path name if it begins with `/' and
     does not parse as a valid RFC 822 address that includes a domain.
     For example,

          /home/world/minbari

     is treated as a file name, but

          /s=molari/o=babylon/@x400gate.way

     is treated as an address. For a file name, a transport must be
     specified using the "file_transport" option. However, if the
     generated path name ends with a forward slash character, it is
     interpreted as a directory name rather than a file name, and
     "directory_transport" is used instead. If it ends with two
     slashes, "directory2_transport" is required. This makes it
     possible to support two different kinds of directory delivery
     simultaneously.

     If a generated path is "/dev/null", delivery to it is bypassed at
     a high level, and the log entry shows `**bypassed**' instead of a
     transport name.  This avoids the need to specify a user and group,
     which are necessary for a genuine delivery to a file. When the
     file name is not "/dev/null", either the director or the transport
     must specify a user and group under which to run the delivery.

   * An item of the form

          :include:<path name>

     may appear in an alias file, in which case a list of further items
     is taken from the given file and included at that point. The items
     in the list are separated by commas or newlines and are not
     subject to expansion, even when the "expand" option is set. If
     this is the first item in an alias list, a colon must be used to
     terminate the alias name.  This example is incorrect:

          list1    :include:/opt/lists/list1

     It must be given as

          list1:   :include:/opt/lists/list1

   * Sometimes you want to throw away mail to a particular local part.
     An alias entry with no addresses causes Exim to generate an error,
     so that cannot be used. However, another special item that may
     appear in an alias file is

          :blackhole:

     which does what its name implies. No delivery is done for it, and
     no error message is generated. If this is the first item in an
     alias list, a colon must be used to terminate the alias name.

     This used to be more efficient than directing a message to
     "/dev/null" because it happens at directing time, and also there
     was no need to specify a user and group to run the transport
     process for delivery to a file. However, from Exim version 1.90
     onwards "/dev/null" is recognized specially, and handled in
     essentially the same way as ":blackhole:".

   * An attempt to deliver to a particular local part can be deferred
     or forced to fail by aliasing the local part to

          :defer:
          or
          :fail:

     respectively. As this is normally the only item in an alias list,
     a colon must be used to terminate the alias name. When an alias
     list contains such an item, it applies to the entire alias; any
     other items in the list are ignored (":blackhole:" is different).
     Any text following ":fail:" or ":defer:" is placed in the error
     text associated with the failure.  For example:

          X.Employee:  :fail: Gone away, no forwarding address

     In the case of an address that is being verified for the SMTP RCPT
     or VRFY commands, the text is included in the SMTP error response,
     which has a 451 code for a ":defer:" failure, and 550 for ":fail:".
     In other cases it is included in the error message that Exim
     generates.

     Normally the error text is the rest of the alias entry - a comma
     does not terminate it - but a newline does act as a terminator.
     Newlines are not normally present in alias expansions. In
     "lsearch" lookups they are removed as part of the continuation
     process, but they may exist in other kinds of lookup and in
     ":include:"d files.

     During message delivery, an alias containing ":fail:" causes an
     immediate failure of the incoming address, whereas ":defer:"
     causes the message to remain on the queue so that a subsequent
     delivery attempt can happen at a later time.  If an address is
     ":defer:"red for too long, it will ultimately fail, since normal
     retry rules apply.

   * Sometimes it is useful to use a search type with a default (see
     chapter "File and database lookups") for aliases. However, there
     may be a need for exceptions to the default. These can be handled
     by aliasing them to

          :unknown:

     This differs from ":fail:" in that it causes "aliasfile" to pass
     the address on to the next director, whereas ":fail:" forces
     directing to fail immediately. If ":unknown:" is the first item in
     an alias list, a colon must be used to terminate the alias name.


File: exim.info,  Node: Duplicate addresses,  Next: Repeated alias expansion,  Prev: Types of alias item,  Up: The aliasfile director

Duplicate addresses
===================

Exim removes duplicate addresses from the list to which it is
delivering, so as to deliver just one copy to each address. This does
not apply to deliveries directed at pipes by different immediate parent
addresses, but an indirect aliasing scheme of the type

     pipe:       |/some/command ${local_part}
     localpart1: pipe
     localpart2: pipe

does not work with a message that is addressed to both local parts,
because when the second is aliased to the intermediate local part
`pipe' it gets discarded as being the same as a previously handled
address. However, a scheme such as

     localpart1: |/some/command ${local_part}
     localpart2: |/some/command ${local_part}

does result in two different pipe deliveries, because the immediate
parents of the pipes are distinct.


File: exim.info,  Node: Repeated alias expansion,  Next: Errors in alias files,  Prev: Duplicate addresses,  Up: The aliasfile director

Repeated alias expansion
========================

When a message cannot be delivered to all of its recipients immediately,
leading to two or more delivery attempts, alias expansion is carried
out afresh each time for those addresses whose children were not all
previously delivered.  If an alias is being used as a mailing list,
this can lead to new members of the list receiving copies of old
messages. The "one_time" option can be used to avoid this.


File: exim.info,  Node: Errors in alias files,  Next: Aliasfile private options,  Prev: Repeated alias expansion,  Up: The aliasfile director

Errors in alias files
=====================

If "skip_syntax_errors" is set, a malformed address that causes a
parsing error is skipped, and an entry is written to the main log. This
may be useful for mailing lists that are automatically managed, but
note the inherent danger.  Otherwise, if an error is detected while
generating the list of new addresses, the message is frozen, except for
the special case of inability to open an included file, when
"no_freeze_missing_include" is set. In this case, delivery is simply
deferred.


File: exim.info,  Node: Aliasfile private options,  Prev: Errors in alias files,  Up: The aliasfile director

Aliasfile private options
=========================

This section lists the private options that "aliasfile" does not have
in common with "forwardfile". Those that they share are given in chapter
"Options common to the aliasfile and forwardfile directors".



* Menu:

* expand (aliasfile)::
* file (aliasfile)::
* forbid_special (aliasfile)::
* include_domain (aliasfile)::
* optional (aliasfile)::
* queries (aliasfile)::
* query (aliasfile)::
* search_type (aliasfile)::


File: exim.info,  Node: expand (aliasfile),  Next: file (aliasfile),  Prev: Aliasfile private options,  Up: Aliasfile private options

expand (aliasfile) _option_
---------------------------

Type: boolean
Default: false

If this option is set true, the text obtained by looking up the local
part is passed through the string expansion mechanism before being
interpreted as a list of alias items. Addresses that are subsequently
added by means of the `include' mechanism are not expanded.


File: exim.info,  Node: file (aliasfile),  Next: forbid_special (aliasfile),  Prev: expand (aliasfile),  Up: Aliasfile private options

file (aliasfile) _option_
-------------------------

Type: string, expanded
Default: unset

This option specifies the name of the alias file, and it must be set if
"search_type" specifies a single-key lookup; if it does not, an error
occurs.  (For query-style lookups, "query" must be set instead.) See
chapter "File and database lookups" for details of different lookup
styles.  The string is expanded before use; if expansion fails, Exim
panics. The resulting string must be an absolute path for linear search
and DBM lookups. If the original string does not start with `/' or `$'
in these cases, Exim gives a configuration error when it starts up;
otherwise, if an expanded string does not begin with `/' delivery is
frozen.


File: exim.info,  Node: forbid_special (aliasfile),  Next: include_domain (aliasfile),  Prev: file (aliasfile),  Up: Aliasfile private options

forbid_special (aliasfile) _option_
-----------------------------------

Type: boolean
Default: false

If this option is set, the special items ":defer:", ":fail:",
":blackhole:" and ":unknown:" are forbidden. If any are encountered,
delivery is deferred.


File: exim.info,  Node: include_domain (aliasfile),  Next: optional (aliasfile),  Prev: forbid_special (aliasfile),  Up: Aliasfile private options

include_domain (aliasfile) _option_
-----------------------------------

Type: boolean
Default: false

Setting this option true causes the key that is looked up to be
`local-part@domain' instead of just `local-part'. Thus a single file
can be used to hold aliases for many local domains. This option has no
effect if the search type specifies a query-style lookup.

If you want include defaults for each domain in an alias file in the
form

     *@domain1:  default@domain1
     *@domain2:  default@domain2

then you need to include `*@' in the search type (for example, "dbm*@").
See section "Single-key lookup types" in chapter "File and database
lookups" for details of this kind of search.


File: exim.info,  Node: optional (aliasfile),  Next: queries (aliasfile),  Prev: include_domain (aliasfile),  Up: Aliasfile private options

optional (aliasfile) _option_
-----------------------------

Type: boolean
Default: false

For a single-key lookup type, if the file cannot be opened because it
does not exist (the ENOENT error) and this option is set, the director
simply declines to handle the address.  Otherwise any failure to open
the file causes an entry to be written to the log and delivery to be
deferred.

For a query-style lookup type, "optional" causes the director to
decline if no query can be completed (for example, all databases are
down). Without "optional", delivery is deferred.


File: exim.info,  Node: queries (aliasfile),  Next: query (aliasfile),  Prev: optional (aliasfile),  Up: Aliasfile private options

queries (aliasfile) _option_
----------------------------

Type: string, expanded
Default: unset

This option is an alternative to "query"; the two options are mutually
exclusive. The difference is that "queries" contains a colon-separated
list of queries, which are tried in order until one succeeds or defers,
or all fail.  Any colon characters actually required in an individual
query must be doubled, in order that they not be treated as query
separators.


File: exim.info,  Node: query (aliasfile),  Next: search_type (aliasfile),  Prev: queries (aliasfile),  Up: Aliasfile private options

query (aliasfile) _option_
--------------------------

Type: string, expanded
Default: unset

This option specifies a database query, and either it or "queries" must
be set if "search_type" specifies a query-style lookup; if neither is
set, an error occurs. (For single-key lookups, "file" must be set
instead.) See chapter "File and database lookups" for details of
different lookup styles. The query is expanded before use, and would
normally contain a reference to the local part.  For example,

     search_type = nisplus
     query = [alias=${local_part}],mail_aliases.org_dir:expansion

could be used for a NIS+ lookup.  Sometimes a lookup cannot be
completed (for example, a NIS+ database might be inaccessible) and in
this case the director causes delivery to be deferred.


File: exim.info,  Node: search_type (aliasfile),  Prev: query (aliasfile),  Up: Aliasfile private options

search_type (aliasfile) _option_
--------------------------------

Type: string
Default: unset

This option must be set to the name of a supported search type
(`lsearch', `dbm', etc.), specifying the type of data lookup. For
query-style lookups, the "query" option specifies the search query, and
"file" must not be set.  For the other search types, "file" is required
and "query" must not be set. See chapter "File and database lookups"
for details of the different lookup styles.

Single-key search types for "aliasfile" can be preceded by `partial-'
and/or followed by `*'. The former isn't likely to be useful very
often, but the latter provides a default facility. Note, however, that
if two addresses in the same message provoke the use of the default,
only one copy gets delivered, but any added "Envelope-to:" header
contains all the original addresses.  Exceptions to the default can be
set up by aliasing them to ":unknown:".


File: exim.info,  Node: The forwardfile director,  Next: The localuser director,  Prev: The aliasfile director,  Up: Top

The forwardfile director
************************

The "forwardfile" director can be used for two different but related
operations. Its effect is to replace a local part with a list of
addresses, file names, or pipe commands, taken from a single file, or
from an inline string.  It gets its name from the common case where the
file is in a user's home directory and is called `.forward', but
another common use is for expanding mailing lists, which are discussed
in more detail in chapter "Using Exim to handle mailing lists".

A standard transport must not be specified for this director. That is,
the generic "transport" option must not be set. A configuration error
occurs if one is given. However, the special transports for handling
files, pipes, and autoreplies must be set if needed.

When handling a user's `.forward' file, a uid, gid, and home directory
are commonly obtained from the password file by calling "getpwnam()".
However, these may alternatively be specified by options to the
director, in which case "getpwnam()" is not called.



* Menu:

* Forward file items::
* Repeated forwarding expansion::
* Errors in forward files::
* Filter files::
* The home directory::
* Special treatment of home_directory and current_directory::
* Forwardfile private options::


File: exim.info,  Node: Forward file items,  Next: Repeated forwarding expansion,  Prev: The forwardfile director,  Up: The forwardfile director

Forward file items
==================

The contents of the file or inline string are a list of addresses, file
names, or pipe commands, separated by commas or newlines. Items that
are empty are ignored. This includes items consisting solely of RFC 822
address comments. If an item is entirely enclosed in double quotes,
these are removed, but otherwise double quotes are retained, because
some forms of mail address require the use of double quotes, though
never enclosing the whole address.

Lines starting with a # character are comments, and are ignored, and #
may also appear following a comma, in which case everything between the
# and the end of the line is ignored. If the file is empty, or contains
only blank lines and comments, the director behaves as if it did not
exist.

If a message is addressed to two or more different local parts, each of
which results in an expansion that generates an identical file name or
pipe command, different deliveries occur, though of course each
delivery process runs with different values in the LOCAL_PART
environment variable, and with different uids (in the common case).
This happens only if the immediate ancestors of the pipes or files are
different local parts. If several different local parts generate an
intermediate alias which in turn generates a pipe or file delivery,
only a single delivery is done, because the duplicate intermediate
addresses are discarded.

   * An address item may safely be the same local part as the one
     currently under consideration, because a director is automatically
     skipped if any ancestor has the same local part and was processed
     by that director. Thus a user with login name "spqr" who wants to
     preserve a copy of mail and also forward it somewhere else can set
     up a file such as

          spqr, spqr@st.else.where

     without provoking a loop.  A backslash before an unqualified local
     part is permitted for compatibility with other mailers, but is not
     necessary for loop prevention.  The presence or absence of a
     backslash does, however, make a difference when there is more than
     one local domain. Without a backslash, an unqualified local part
     is qualified with the contents of "qualify_recipient" unless
     "qualify_preserve_domain" is set, but if a backslash is present,
     the local part is always qualified with the domain of the incoming
     address.

     Care must be taken if there are alias names for local users. For
     example if the system alias file contains

          Sam.Reman: spqr

     then

          Sam.Reman, spqr@reme.else.where

     in "spqr"'s forward file fails on an incoming message addressed to
     "Sam.Reman", because the "aliasfile" director does not process
     "Sam.Reman" the second time round, having previously done so.  The
     forward file should really contain

          spqr, spqr@reme.else.where

     but because this is such a common error, the "check_ancestor"
     option (see chapter "Options common to the aliasfile and
     forwardfile directors") exists to provide a way to get round it.

   * An item is interpreted as a file name if it begins with `/' and
     does not parse as a valid RFC 822 address that includes a domain.
     For example,

          /home/world/shadow

     is treated as a file name, but

          /s=molari/o=babylon/@x400gate.way

     is treated as an address.  For a file name, a transport must be
     specified using the "file_transport" option. However, if the
     generated path name ends with a forward slash character, it is
     interpreted as a directory name rather than a file name, and
     "directory_transport" is used instead. If it ends with two slashes,
     "directory2_transport" is required. This makes it possible to
     support two different kinds of directory delivery simultaneously.

     If an item is "/dev/null", delivery to it is bypassed at a high
     level, and the log entry shows `**bypassed**' instead of a
     transport name. This avoids the need for a user and group, which
     are necessary for a genuine delivery to a file. When the file name
     is not "/dev/null", either the director or the transport must
     specify a user and group under which to run the delivery. If
     "check_local_user" is set, the uid and gid from the "passwd" file
     are used as defaults for the generic "user" and "group" options.

   * An item is treated as a pipe command if it begins with `|' and
     does not parse as a valid RFC 822 address that includes a domain.
     A transport for running the command must be specified by the
     "pipe_transport" option. Either the director or the transport must
     specify a user and group under which to run the delivery.  If
     "check_local_user" is set, the uid and gid from the "passwd" file
     are used as defaults for the generic "user" and "group" options.

     Both single and double quotes can be used for enclosing individual
     arguments to the pipe command; no interpretation of escapes is
     done for single quotes. If the command contains a comma character,
     it is necessary to put the whole item in double quotes, for
     example:

          "|/some/command ready,steady,go"

     since items are terminated by commas. Do not, however, quote just
     the command.  An item such as

          |"/some/command ready,steady,go"

     is interpreted as a pipe with a rather strange command name, and
     no arguments.

   * Instead of an address, file name, or pipe command, an item of the
     form

          :include:<path name>

     may appear, in which case a list of addresses is taken from the
     given file and included at that point, unless the "forbid_include"
     option is set.  There are some security considerations when such
     an item is included in a user's `.forward' file:

       a. If the "seteuid()" function is being used to read the main
          file as a specific user (see "seteuid" below) then the
          included file is read as the same user.

       b. Otherwise Exim is running as root at this point. If
          "check_local_user" is set, or if an explicit directory is
          specified by "file_directory", then any included files must
          be within the home or given directory, and no symbolic links
          are permitted below the directory name.

       c. If neither "check_local_user" nor "file_directory" is set
          when "seteuid()" is not in use, included files are not
          permitted.



File: exim.info,  Node: Repeated forwarding expansion,  Next: Errors in forward files,  Prev: Forward file items,  Up: The forwardfile director

Repeated forwarding expansion
=============================

When a message cannot be delivered to all of its recipients immediately,
leading to two or more delivery attempts, forwarding expansion is
carried out afresh each time for those addresses whose children were
not all previously delivered. If a forward file is being used as a
mailing list, this can lead to new members of the list receiving copies
of old messages. The "one_time" option can be used to avoid this.


File: exim.info,  Node: Errors in forward files,  Next: Filter files,  Prev: Repeated forwarding expansion,  Up: The forwardfile director

Errors in forward files
=======================

If "skip_syntax_errors" is set, a malformed address that causes a
parsing error is skipped, and an entry is written to the main log. This
may be useful for mailing lists that are automatically managed, but
note the inherent danger.  The option should never be set for users'
`.forward' files.  Otherwise, if any error is detected while generating
the list of new addresses, the message is frozen, except for the
special case of inability to open an included file when
"no_freeze_missing_include" is set. In this case, delivery is simply
deferred.


File: exim.info,  Node: Filter files,  Next: The home directory,  Prev: Errors in forward files,  Up: The forwardfile director

Filter files
============

As an alternative to treating the file as a simple list of addresses,
the "forwardfile" director can be configured, by means of the "filter"
option, to read a file and interpret it as a list of "filtering"
instructions if it conforms to a specific format. The instructions can
specify various actions such as appending the message to certain mail
folders, or forwarding it to other users, predicated on the content of
the message. Details of the syntax and semantics of filter files are
described in a separate document entitled "Exim's interface to mail
filtering"; this is intended for use by end users.  If filters are
permitted to generate mail messages (see "forbid_reply") then the
"reply_transport" option must be set.


File: exim.info,  Node: The home directory,  Next: Special treatment of home_directory and current_directory,  Prev: Filter files,  Up: The forwardfile director

The home directory
==================

The $home expansion variable can be used in a number of local options
for "forwardfile". Its value depends on the way the options are set up,
as follows:

   * If "check_local_user" is set and "file_directory" is unset, $home
     is set to the user's home directory when expanding the "file"
     option that specifies a forward or filter file.

   * If "check_local_user" is unset and "file_directory" is set, $home
     is set to the expanded value of "file_directory" when expanding
     the "file" option. If $home appears in "file_directory", its
     substitution value is the empty string.

   * If both "check_local_user" and "file_directory" are set, $home
     contains the user's home directory when expanding
     "file_directory", but subsequently $home contains the value of
     "file_directory" when expanding the "file" option.

   * If neither "check_local_user" not "file_directory" are set, $home
     is empty.

If the generic "require_files" option, or any other expanded option,
contains $home, it takes the same value as it does when expanding the
"file" option, and this value is also used for $home if encountered in
a filter file, and as the default value to pass with the address when a
pipe or file delivery is generated.

Note that the value of the "home_directory" generic option is not used
during directing; it specifies a directory for use at transport time.


File: exim.info,  Node: Special treatment of home_directory and current_directory,  Next: Forwardfile private options,  Prev: The home directory,  Up: The forwardfile director

Special treatment of home_directory and current_directory
=========================================================

The generic options "home_directory" and "current_directory" (specified
in chapter "Additional generic options for directors") are handled in a
special way by the "forwardfile" director. Neither has any effect
during the running of the director; they act only when it directs an
address to a local transport because it specifies a file name, pipe
command, or autoreply - the values are passed with the address for use
at transport time.

If "home_directory" is not set, the directory specified by
"file_directory", or if that is not set, the home directory obtained
from "check_local_user" is used as the default value.

In installations where users' `.forward' files are not kept in their
home directories, both "check_local_user" and "file_directory" may be
set, which leads to the "file_directory" value being used as the
default, when the actual home directory may be wanted. It is no good
specifying

     home_directory = $home

because the same value is used for $home. A special string value is
therefore provided for use in this case. If "home_directory" is set to
the string `check_local_user' it is converted into the user's home
directory path. The same magic string can also be used for
"current_directory".


File: exim.info,  Node: Forwardfile private options,  Prev: Special treatment of home_directory and current_directory,  Up: The forwardfile director

Forwardfile private options
===========================

This section lists the private options that "forwardfile" does not have
in common with "aliasfile". Those that they share are given in chapter
"Options common to the aliasfile and forwardfile directors".



* Menu:

* allow_system_actions (forwardfile)::
* check_group (forwardfile)::
* check_local_user (forwardfile)::
* data (forwardfile)::
* file (forwardfile)::
* file_directory (forwardfile)::
* filter (forwardfile)::
* forbid_filter_existstest (forwardfile)::
* forbid_filter_logwrite (forwardfile)::
* forbid_filter_lookup (forwardfile)::
* forbid_filter_perl (forwardfile)::
* forbid_filter_reply (forwardfile)::
* ignore_eacces (forwardfile)::
* ignore_enotdir (forwardfile)::
* match_directory (forwardfile)::
* reply_transport (forwardfile)::
* seteuid (forwardfile)::


File: exim.info,  Node: allow_system_actions (forwardfile),  Next: check_group (forwardfile),  Prev: Forwardfile private options,  Up: Forwardfile private options

allow_system_actions (forwardfile) _option_
-------------------------------------------

Type: boolean
Default: false

Setting this option permits the use of "freeze" and "fail" in filter
files.  This should not be set on the director for users' `.forward'
files, but can be useful if you want to run a system-wide filter for
each address, as opposed to the system filter, which runs just once per
message. See chapter "System-wide message filtering".


File: exim.info,  Node: check_group (forwardfile),  Next: check_local_user (forwardfile),  Prev: allow_system_actions (forwardfile),  Up: Forwardfile private options

check_group (forwardfile) _option_
----------------------------------

Type: boolean
Default: false

The group of the file is checked only when this option is set. If
"check_local_user" is set, the user's default group is permitted;
otherwise the group must be one of those listed in the "owngroups"
option.


File: exim.info,  Node: check_local_user (forwardfile),  Next: data (forwardfile),  Prev: check_group (forwardfile),  Up: Forwardfile private options

check_local_user (forwardfile) _option_
---------------------------------------

Type: boolean
Default: true

If this option is true, the local part that is passed to this director
is checked to ensure that it is the login of a local user by calling the
"getpwnam()" function. The director declines to handle the address if
it is not.  In addition, when this option is true, the string specified
for the "file" option is taken as relative to the user's home directory
if it is not an absolute path, unless the "file_directory" option is
set.

When this option is set, the local user is always one of the permitted
owners of the file, and the local user's uid is used when reading the
forward file if the "seteuid" option is set or if the global security
setting is not `setuid'.  In addition the uid and gid read from the
"passwd" file are used as defaults for the generic "user" and "group"
options.


File: exim.info,  Node: data (forwardfile),  Next: file (forwardfile),  Prev: check_local_user (forwardfile),  Up: Forwardfile private options

data (forwardfile) _option_
---------------------------

Type: string, expanded
Default: unset

This option is mutually exclusive with "file". One or other of them
must be set, but not both. The contents of "data" are expanded, and
then used as the list of forwarding items, or as a set of filtering
instructions, just as if they were the contents of the file.
Essentially, "data" allows you to provide the filtering instructions
inline, but because it is expanded, you can, for example, look them up
in a database or indexed file. When filtering instructions are used,
the string must start off with `#Exim filter', and all comments in the
string, including this initial one, must be terminated with newline
characters. For example:

     data = "#Exim filter\n\
            if $h_to: contains Exim then save $home/mail/exim endif"

If you are reading the data from a database where newlines cannot be
included, you can use the ${sg} expansion item to turn the escape
string of your choice into a newline.


File: exim.info,  Node: file (forwardfile),  Next: file_directory (forwardfile),  Prev: data (forwardfile),  Up: Forwardfile private options

file (forwardfile) _option_
---------------------------

Type: string, expanded
Default: unset

This option is mutually exclusive with "data". One or other of them
must be set, but not both. The contents of "file" are expanded - see
above for a discussion of the "home" expansion variable. If expansion
fails, Exim defers the address and freezes the message.  The expanded
string is interpreted as a file name, and must start with a slash
character unless "check_local_user" is true, or a "file_directory"
option is set. A non-absolute path is interpreted relative to the
"file_directory" setting if it exists; otherwise it is interpreted
relative to the user's home directory. The contents of the file are the
list of forwarding items or a set of filtering instructions.

If a non-absolute path is used, Exim uses the "stat()" function to
check the directory before attempting to open the file therein. If the
directory is inaccessible, the delivery to the current address is
deferred. This distinguishes between the cases of a non-existent file
(where the director cannot handle the address, and must decline) and an
unmounted NFS directory (where delivery should be deferred). Thus the
difference between the two settings

     file = .forward
     file = $home/.forward

is that in the second case the directory is not checked with "stat()".

If the file exists but is empty or contains only blank and comment lines
starting with #, Exim behaves as if it did not exist, and the director
declines to handle the address. Note that this is not the case when the
file contains syntactically valid items that happen to yield empty
addresses, for example, items containing only RFC 822 address comments.


File: exim.info,  Node: file_directory (forwardfile),  Next: filter (forwardfile),  Prev: file (forwardfile),  Up: Forwardfile private options

file_directory (forwardfile) _option_
-------------------------------------

Type: string, expanded
Default: unset

The string is expanded before use - see above for a discussion of the
"home" expansion variable. The option sets a directory path which is
used if the "file" option does not specify an absolute path. This on
its own is not very useful, since the directory string could just as
well be prepended to the file string. However, if a separate directory
is given, it is treated like a directory obtained from
"check_local_user", and its existence is tested before trying to open
the file. If the directory appears not to exist, delivery is deferred.
Thus, a setting such as

     file_directory = /usr/forwards
     file = ${local_part}.forward

defers delivery if "/usr/forwards" appears not to exist. This can be
useful if the directory is NFS mounted. If "check_local_user" is also
set, "file_directory" takes precedence in determining the directory
name for non-absolute files.

If "forwardfile" sets up a delivery to a file or a pipe command and the
"home_directory" option is not set, the directory specified by
"file_directory", or if that is not set, the home directory obtained
from "check_local_user" is associated with the address during delivery.


File: exim.info,  Node: filter (forwardfile),  Next: forbid_filter_existstest (forwardfile),  Prev: file_directory (forwardfile),  Up: Forwardfile private options

filter (forwardfile) _option_
-----------------------------

Type: boolean
Default: false

If this option is set, and the forward file or inline forwarding data
starts with the text `# Exim filter', it is interpreted as a set of
filtering commands instead of a list of forwarding addresses. Details
of the syntax and semantics of filter files are described in a separate
document entitled "Exim's interface to mail filtering"; this is
intended for use by end users.

In addition to the commands described therein, there are some extra
commands that are permitted only in system filter files, or if
"allow_system_actions" is set. These are described in chapter
"System-wide message filtering".

Filter files may contain string expansions, but some administrators may
not want to permit those expansion features that involve accessing
files. The options "forbid_filter_existstest", "forbid_filter_lookup",
and "forbid_filter_perl" (see below) can be used to lock out these
features.

The logging facility in filter files is available only if the filter is
being run under some unprivileged uid. The system configuration must
specify that "seteuid()" is available, either "user" or
"check_local_user" must be set on the director, "forbid_filter_log"
must not be set, and the global "security" setting must not be
`setuid'. Writing the log takes place while the filter file is being
interpreted, that is, at directing time. It does not queue up for later
like the delivery commands. The reason for this is so that a log file
need be opened only once for several write operations.


File: exim.info,  Node: forbid_filter_existstest (forwardfile),  Next: forbid_filter_logwrite (forwardfile),  Prev: filter (forwardfile),  Up: Forwardfile private options

forbid_filter_existstest (forwardfile) _option_
-----------------------------------------------

Type: boolean
Default: false

If this option is true, string expansions in filter files are not
allowed to make use of the "exists" condition.


File: exim.info,  Node: forbid_filter_logwrite (forwardfile),  Next: forbid_filter_lookup (forwardfile),  Prev: forbid_filter_existstest (forwardfile),  Up: Forwardfile private options

forbid_filter_logwrite (forwardfile) _option_
---------------------------------------------

Type: boolean
Default: false

If this option is true, use of the logging facility in filter files is
not permitted. This is in any case available only if the filter is
being run under some unprivileged uid, which is normally the case for
ordinary users' `.forward' files on a system with "seteuid()" available.


File: exim.info,  Node: forbid_filter_lookup (forwardfile),  Next: forbid_filter_perl (forwardfile),  Prev: forbid_filter_logwrite (forwardfile),  Up: Forwardfile private options

forbid_filter_lookup (forwardfile) _option_
-------------------------------------------

Type: boolean
Default: false

If this option is true, string expansions in filter files are not
allowed to make use of "lookup" items.


File: exim.info,  Node: forbid_filter_perl (forwardfile),  Next: forbid_filter_reply (forwardfile),  Prev: forbid_filter_lookup (forwardfile),  Up: Forwardfile private options

forbid_filter_perl (forwardfile) _option_
-----------------------------------------

Type: boolean
Default: false

This option is available only if Exim is built with embedded Perl
support. If it is true, string expansions in filter files are not
allowed to make use of the embedded Perl support.


File: exim.info,  Node: forbid_filter_reply (forwardfile),  Next: ignore_eacces (forwardfile),  Prev: forbid_filter_perl (forwardfile),  Up: Forwardfile private options

forbid_filter_reply (forwardfile) _option_
------------------------------------------

Type: boolean
Default: false

If this option is true, this director may not generate an automatic
reply message. If it attempts to do so, a delivery failure occurs.
Automatic replies can be generated only from filter files, not from
traditional forward files.


File: exim.info,  Node: ignore_eacces (forwardfile),  Next: ignore_enotdir (forwardfile),  Prev: forbid_filter_reply (forwardfile),  Up: Forwardfile private options

ignore_eacces (forwardfile) _option_
------------------------------------

Type: boolean
Default: false

If this option is set and an attempt to open the forward file yields the
EACCES error (permission denied) then "forwardfile" behaves as if the
file did not exist.


File: exim.info,  Node: ignore_enotdir (forwardfile),  Next: match_directory (forwardfile),  Prev: ignore_eacces (forwardfile),  Up: Forwardfile private options

ignore_enotdir (forwardfile) _option_
-------------------------------------

Type: boolean
Default: false

If this option is set and an attempt to open the forward file yields the
ENOTDIR error (something on the path is not a directory) then
"forwardfile" behaves as if the file did not exist.


File: exim.info,  Node: match_directory (forwardfile),  Next: reply_transport (forwardfile),  Prev: ignore_enotdir (forwardfile),  Up: Forwardfile private options

match_directory (forwardfile) _option_
--------------------------------------

Type: string, expanded
Default: unset

If this option is set with "check_local_user", the user's home
directory, as obtained from "getpwnam()", must match the given string.
If it does not, the director declines to handle the address. The string
is expanded before use. If the expansion fails, Exim defers the address
and freezes the message, unless the failure was explicitly triggered by
a `fail' item in a conditional sub-expression in the expansion, in
which case the director just declines to handle the address.

If the expanded string starts with an asterisk, the remainder must match
the end of the home directory name; if it starts with a circumflex, a
regular expression match is performed. In fact, the matching process is
the same as is used for domain list items and may include file lookups.

If the pattern starts with an exclamation mark, the user's home
directory must not match the rest of the given string. For example, with

     match_directory = !^/group

the director declines if the user's home directory starts with "/group".


File: exim.info,  Node: reply_transport (forwardfile),  Next: seteuid (forwardfile),  Prev: match_directory (forwardfile),  Up: Forwardfile private options

reply_transport (forwardfile) _option_
--------------------------------------

Type: string, expanded
Default: unset

A "forwardfile" director sets up a delivery to an "autoreply" transport
when a "mail" or "vacation" command is used in a filter file.  The
transport used is specified by this option, which, after expansion,
must be the name of a configured transport.


File: exim.info,  Node: seteuid (forwardfile),  Prev: reply_transport (forwardfile),  Up: Forwardfile private options

seteuid (forwardfile) _option_
------------------------------

Type: boolean
Default: false

This option may not be set unless the compile-time configuration in the
OS-specific configuration files specifies that the "seteuid()" function
is available in the operating system. In addition, either the
"check_local_user" or the generic "user" and "group" options must be
set. A configuration error occurs if these conditions do not hold.

When this option is true, the "seteuid()" and "setegid()" functions are
called to change the effective uid and gid before accessing the home
directory and the file. If both "check_local_user" and "user" are set,
the uid is taken from the latter. If the generic "initgroups" option is
set, "initgroups()" is called to initialise the group list with all the
user's groups. The user remains set during interpretation of a filter
file; if it writes log entries the log file must be accessible to the
uid or gid. Changing uid is necessary in two circumstances:

  a. When Exim is configured to change the effective uid from root to
     the Exim user (using "seteuid()") while running the directors. See
     chapter "Security considerations" for details.

  b. When users' home directories are NFS mounted, and root access is
     not exported to the local host, to allow for cases when the files
     are not world-readable.

The "forwardfile" director can detect the first of these cases, and it
always uses "seteuid()", regardless of the setting of this option,
since it does not make sense to do otherwise.

On a system without the "seteuid()" function, but with NFS home
directories that do not export root, it is necessary for forward files
to be world-readable.


File: exim.info,  Node: The localuser director,  Next: The smartuser director,  Prev: The forwardfile director,  Up: Top

The localuser director
**********************

The "localuser" director checks whether the local part of an address is
the login of a local user, by calling the "getpwnam()" function. If it
is, and if other conditions set by options are met, it accepts the
address and sets up a transport for it. The generic "transport" option
must always be specified, unless the generic "verify_only" option is
set.

The user's uid and  gid are set up by default to be used while running
the delivery process. If the generic "home_directory" option (see
chapter "Additional generic options for directors") is unset, the
user's home directory is passed to the transport for use during
delivery. Setting

     home_directory = $home

does not work, because $home is not set during the expansion of
"home_directory".

When processing the "require_files" generic option, the value of $home
is the value of "home_directory" if set, and otherwise the user's home
directory.  Using "require_files" it is possible to pick out all users
with particular files in their home directories and route their mail to
a specific transport. This could be used, for example, to check for a
".procmailrc" file and then to direct delivery via "procmail" if one is
found.



* Menu:

* match_directory (localuser)::
* The localuser director (continued)::


File: exim.info,  Node: match_directory (localuser),  Next: The localuser director (continued),  Prev: The localuser director,  Up: The localuser director

match_directory (localuser) _option_
------------------------------------

Type: string, expanded
Default: unset

If this option is set, the user's home directory, as obtained from
"getpwnam()", must match the given string. If it does not, the director
declines to handle the address. This provides a way of partitioning the
local users by home directory. The string is expanded before use. If
the expansion fails, Exim defers the address and freezes the message,
unless the failure was explicitly triggered by a `fail' item in a
conditional sub-expression in the expansion, in which case the director
just declines to handle the address.

If the expanded string starts with an asterisk, the remainder must match
the end of the home directory name; if it starts with a circumflex, a
regular expression match is performed. In fact, the matching process is
the same as is used for domain list items and may include file lookups.

If the pattern starts with an exclamation mark, the user's home
directory must not match the rest of the given string. For example, with

     match_directory = !^/group

the director declines if the user's home directory starts with "/group".


File: exim.info,  Node: The localuser director (continued),  Prev: match_directory (localuser),  Up: The localuser director

On central systems at Cambridge University, when a user account is
cancelled, it remains in the password file for a while, with the home
directory set to "/home/CANCELLED". We use the "match_directory" option
to detect mail addressed to such users and bounce it with an
explanatory message.


File: exim.info,  Node: The smartuser director,  Next: Additional generic options for routers,  Prev: The localuser director,  Up: Top

The smartuser director
**********************

The "smartuser" director matches any local part, so it can be used to
handle local addresses that all other directors have declined. It is,
of course, subject to the generic director options, so specific
instances can be used for all addresses in certain domains, or all
local parts with certain prefixes or suffixes, or specific local parts,
or any other generic condition.

If a transport is specified, "smartuser" directs the message to that
transport, either using the original address, or, if "new_address" is
set, using a new envelope address. No checking for duplication takes
place. The original address is available to the transport via the
expansion variables $original_local_part and $original_domain.

If no transport is specified, "new_address" must be set, and "smartuser"
treats its value as if it were a line from an alias file. It must
consist of a comma-separated list of items as defined in section "Types
of alias item" in chapter "The aliasfile director". The special values
":blackhole:", ":defer:", and ":fail:" (but not ":include:") may be
used, and file or pipe items may also appear.  If any new address is a
duplicate of any other address in the message, it is discarded.



* Menu:

* directory_transport (smartuser)::
* directory2_transport (smartuser)::
* file_transport (smartuser)::
* forbid_file (smartuser)::
* forbid_pipe (smartuser)::
* hide_child_in_errmsg (smartuser)::
* new_address (smartuser)::
* panic_expansion_fail (smartuser)::
* pipe_transport (smartuser)::
* qualify_preserve_domain (smartuser)::
* rewrite (smartuser)::


File: exim.info,  Node: directory_transport (smartuser),  Next: directory2_transport (smartuser),  Prev: The smartuser director,  Up: The smartuser director

directory_transport (smartuser) _option_
----------------------------------------

Type: string, expanded
Default: unset

A "smartuser" director sets up a direct delivery to a directory when a
path name ending with a slash is specified as a new `address'. The
transport used is specified by this option, which, after expansion,
must be the name of a configured transport.


File: exim.info,  Node: directory2_transport (smartuser),  Next: file_transport (smartuser),  Prev: directory_transport (smartuser),  Up: The smartuser director

directory2_transport (smartuser) _option_
-----------------------------------------

Type: string, expanded
Default: unset

A "smartuser" director sets up an alternative direct delivery to a
directory when a path name ending with two slashes is specified as a
new `address'. The transport used is specified by this option, which,
after expansion, must be the name of a configured transport.


File: exim.info,  Node: file_transport (smartuser),  Next: forbid_file (smartuser),  Prev: directory2_transport (smartuser),  Up: The smartuser director

file_transport (smartuser) _option_
-----------------------------------

Type: string, expanded
Default: unset

A "smartuser" director sets up a direct delivery to a file when a path
name not ending in a slash is specified as a new `address'. The
transport used is specified by this option, which, after expansion,
must be the name of a configured transport.


File: exim.info,  Node: forbid_file (smartuser),  Next: forbid_pipe (smartuser),  Prev: file_transport (smartuser),  Up: The smartuser director

forbid_file (smartuser) _option_
--------------------------------

Type: boolean
Default: false

If this option is true, this director may not generate a new address
which specifies delivery to a local file or directory. If it attempts
to do so, a delivery failure occurs.


File: exim.info,  Node: forbid_pipe (smartuser),  Next: hide_child_in_errmsg (smartuser),  Prev: forbid_file (smartuser),  Up: The smartuser director

forbid_pipe (smartuser) _option_
--------------------------------

Type: boolean
Default: false

If this option is true, this director may not generate a new address
which specifies delivery to a pipe. If it attempts to do so, a delivery
failure occurs.


File: exim.info,  Node: hide_child_in_errmsg (smartuser),  Next: new_address (smartuser),  Prev: forbid_pipe (smartuser),  Up: The smartuser director

hide_child_in_errmsg (smartuser) _option_
-----------------------------------------

Type: boolean
Default: false

If this option is set true, it prevents Exim from quoting a child
address if it generates a bounce or delay message for it. Instead it
says `an address generated from <the top level address>'. Of course,
this applies only to bounces generated locally. If a message is
forwarded to another host, its bounce may well quote the generated
address.


File: exim.info,  Node: new_address (smartuser),  Next: panic_expansion_fail (smartuser),  Prev: hide_child_in_errmsg (smartuser),  Up: The smartuser director

new_address (smartuser) _option_
--------------------------------

Type: string, expanded
Default: unset

When "transport" is not set, this option is treated like a line from an
alias file. Any unqualified addresses it contains are qualified using
the value of "qualify_recipient". This is the most common configuration
for "smartuser".

When "transport" is set, "new_address" specifies a single new address,
to replace the current one in the message's envelope when it is
transported. The address must be qualified (that is, contain an @
character).

In both cases, new addresses are rewritten by Exim's normal rewriting
rules (see chapter "Address rewriting") unless the "rewrite" option is
turned off.

The value of "new_address" is expanded, so settings such as

     new_address = ${quote:$local_part}@some.new.host

can be used, or a file lookup on the local part can be done. Note the
use of the "quote" operator above, to ensure that the local part is
quoted if it contains any special characters.

If the expansion fails as a result of an explicit `fail' item in an
expansion sub-expression, the director just declines to handle the
address. Otherwise, an expansion failure is treated as a serious
configuration error, and causes a panic, unless "panic_expansion_fail"
is set false, in which case the same action is taken as for `fail'.


File: exim.info,  Node: panic_expansion_fail (smartuser),  Next: pipe_transport (smartuser),  Prev: new_address (smartuser),  Up: The smartuser director

panic_expansion_fail (smartuser) _option_
-----------------------------------------

Type: boolean
Default: true

See "new_address" above.


File: exim.info,  Node: pipe_transport (smartuser),  Next: qualify_preserve_domain (smartuser),  Prev: panic_expansion_fail (smartuser),  Up: The smartuser director

pipe_transport (smartuser) _option_
-----------------------------------

Type: string, expanded
Default: unset

A "smartuser" director sets up a direct delivery to a pipe when a string
starting with a vertical bar character is specified as a new `address'.
The transport used is specified by this option, which, after expansion,
must be the name of a configured transport.


File: exim.info,  Node: qualify_preserve_domain (smartuser),  Next: rewrite (smartuser),  Prev: pipe_transport (smartuser),  Up: The smartuser director

qualify_preserve_domain (smartuser) _option_
--------------------------------------------

Type: boolean
Default: false

If this is set and an unqualified address (one without a domain) is
present in "new_address", it is qualified with the domain of the
incoming address instead of the global setting in "qualify_recipient".


File: exim.info,  Node: rewrite (smartuser),  Prev: qualify_preserve_domain (smartuser),  Up: The smartuser director

rewrite (smartuser) _option_
----------------------------

Type: boolean
Default: true

If this option is set false, addresses specified by "new_address" are
not subject to rewriting.


File: exim.info,  Node: Additional generic options for routers,  Next: The domainlist router,  Prev: The smartuser director,  Up: Top

Additional generic options for routers
**************************************

The following additional generic options apply to all routers, in
addition to the common generic options for both directors and routers
which are described in chapter "Generic options common to both
directors and routers". Routers are concerned with addresses whose
domains do not match something in "local_domains".



* Menu:

* ignore_target_hosts (router)::
* pass_on_timeout (router)::
* self (router)::
* translate_ip_address (router)::


File: exim.info,  Node: ignore_target_hosts (router),  Next: pass_on_timeout (router),  Prev: Additional generic options for routers,  Up: Additional generic options for routers

ignore_target_hosts (router) _option_
-------------------------------------

Type: host list, expanded
Default: unset

Although this option is a host list, it would normally contain IP
address entries rather than names. If any host that is looked up by the
router matches an item in this list, Exim behaves as if the host did
not exist. This option allows you to cope with rogue DNS entries like

     some.remote.domain  A  127.0.0.1

by setting

     ignore_target_hosts = 127.0.0.1

on the relevant router. Attempts to mail to such a domain then receive
the `unrouteable domain' error, and verifications fail. This option may
also be useful for ignoring link local IPv6 addresses. The string value
of "ignore_target_hosts" is expanded before use as a list, so it is
possible to make it dependent on the domain that is being routed.


File: exim.info,  Node: pass_on_timeout (router),  Next: self (router),  Prev: ignore_target_hosts (router),  Up: Additional generic options for routers

pass_on_timeout (router) _option_
---------------------------------

Type: boolean
Default: false

If a router times out during a host lookup, it normally causes deferral
of the address. If "pass_on_timeout" is set, the address is passed on
to the next router, overriding "no_more". This may be helpful for
systems that are intermittently connected to the Internet, or those
that want to pass to a smart host any messages that cannot immediately
be delivered.

There are occasional other temporary errors that can occur while doing
DNS lookups. They are treated in the same way as a timeout, and this
option applies to all of them.


File: exim.info,  Node: self (router),  Next: translate_ip_address (router),  Prev: pass_on_timeout (router),  Up: Additional generic options for routers

self (router) _option_
----------------------

Type: string
Default: "freeze"

This option specifies what is to happen if routing a remote address
ends up pointing at the local host (checked by comparing IP addresses),
or at a host whose name matches "hosts_treat_as_local". Normally this
indicates either an error in Exim's configuration (for example, the
domain should be listed as local), or an error in the DNS (for example,
the MX shouldn't point at this host). However, this situation is not
confined to the use of MX records, and the "self" option can be used on
any router.

The default action is to freeze the message. The following alternatives
are provided for use in special cases:

   * "defer"
     Delivery of the message is tried again later.

   * "reroute: <domain>"
     The domain is changed to the given domain, and the address is
     passed back to be reprocessed by the directors and routers. No
     rewriting of headers takes place.

   * "reroute: rewrite: <domain>"
     The domain is changed to the given domain, and the address is
     passed back to be reprocessed by the directors and routers. Any
     headers that contain the original domain are rewritten.

   * "local"
     The address is passed to the directors, as if its domain were a
     local domain, even though it does not match anything in
     "local_domains". This can be used to treat all domains whose
     lowest MX records point to the host as local domains.  During
     subsequent directing and delivery the variable $self_hostname is
     set to the name of the local host that the router encountered.
     This can be used to distinguish between different cases for hosts
     with multiple names.

   * "pass"
     The router declines, passing the address to the following router,
     and overriding "no_more". During subsequent routing and delivery,
     the variable $self_hostname contains the name of the local host
     that the router encountered. This can be used to distinguish
     between different cases for hosts with multiple names. A
     combination of "pass" and "no_more" ensures that only those
     addresses that routed to the local host are passed on. Without
     "no_more", addresses that were declined for other reasons would
     also be passed to the next router.

     In earlier versions of Exim "fail_soft" was used instead of
     "pass". It will remain as a synonym for some time.

   * "fail"
     The router declines, but the address is not passed to any following
     routers. Consequently, delivery fails and an error report is
     generated.

     In earlier versions of Exim "fail_hard" was used instead of
     "fail". It will remain as a synonym for some time.

   * "send"
     The anomaly is ignored and the message is transmitted anyway. This
     setting should be used with extreme caution. It makes sense only
     in cases where the program that is listening on the SMTP port is
     not this version of Exim.  That is, it must be some other MTA, or
     Exim with a different configuration file that handles the domain
     in another way.

When a router just rewrites, that is, does not set up IP addresses, the
"self" option is not relevant.


File: exim.info,  Node: translate_ip_address (router),  Prev: self (router),  Up: Additional generic options for routers

translate_ip_address (router) _option_
--------------------------------------

Type: string, expanded
Default: unset

There exist some rare networking situations (for example, packet radio)
where it is helpful to be able to translate IP addresses generated by
normal routing mechanisms into other IP addresses, thus performing a
kind of manual IP routing. This should be done only if the normal IP
routing of the TCP/IP stack is inadequate or broken. Because this is an
extremely uncommon requirement, the code to support this option is not
included in the Exim binary unless SUPPORT_TRANSLATE_IP_ADDRESS=yes is
set in `Local/Makefile'.

The "translate_ip_address" string is expanded for every IP address
generated by the router, with the generated address set in
$host_address. If the expansion is forced to fail, no action is taken.
If it returns an IP address, that replaces the original address;
otherwise the result is assumed to be a host name - this is looked up
using "gethostbyname()" to produce one or more replacement IP
addresses. For example, to subvert all IP addresses in some specific
networks, this could be added to a router:

     $smc{translate_ip_address = \
       ${lookup{${mask:$host_address/26}}lsearch{/some/file}{$value}fail}}

The file would contain lines like

     10.2.3.128/26    some.host
     10.8.4.34/26     10.44.8.15

You should not make use of this facility unless you really understand
what you are doing.


File: exim.info,  Node: The domainlist router,  Next: The ipliteral router,  Prev: Additional generic options for routers,  Up: Top

The domainlist router
*********************

The "domainlist" router compares a list of domain patterns with the
domain it is trying to route. When a match is found, the information
associated with the pattern can specify several different actions:

   * The message can be sent to a specific host, or one of a number of
     hosts.

   * The domain name can be replaced by a new name, which can be

       a. passed to the next router; or

       b. looked up directly in the DNS, with or without MX processing;
          or

       c. looked up using "gethostbyname()".

     Of course, "gethostbyname()" may well do its own DNS lookup, but
     it does not do MX processing, and it may also reference other
     sources of information, such as "/etc/hosts". When Exim is
     compiled with IPv6 support, if a host that is looked up in the DNS
     has both A and AAAA or A6 records, all the addresses are used.

The list of patterns can be specified as an option string, or looked up
in a file or database, or both; at least one of "route_list",
"route_file", "route_query", or "route_queries" must be set. A
transport must be set when the routing is completed by this router,
that is, when the address is not passed on to subsequent routers,
unless "verify_only" is set.  Each routing entry can specify its own
transport, with the generic "transport" option acting as a default for
those that don't.



* Menu:

* host_find_failed (domainlist)::
* hosts_randomize (domainlist)::
* modemask (domainlist)::
* owners (domainlist)::
* owngroups (domainlist)::
* qualify_single (domainlist)::
* route_file (domainlist)::
* route_list (domainlist)::
* route_queries (domainlist)::
* route_query (domainlist)::
* search_parents (domainlist)::
* search_type (domainlist)::
* Routing rules::
* Host list format::
* Options format::
* Application of routing rules::
* Domainlist examples::


File: exim.info,  Node: host_find_failed (domainlist),  Next: hosts_randomize (domainlist),  Prev: The domainlist router,  Up: The domainlist router

host_find_failed (domainlist) _option_
--------------------------------------

Type: string
Default: "freeze"

This option controls what happens if a host which "domainlist" tries to
look up because an address has been specifically routed to it does not
exist. The option can be set to one of

     freeze
     defer
     pass
     fail

The default assumes that this state is a serious configuration error.
The difference between `pass' and `fail' is that the former causes the
address to be passed to the next router, overriding "no_more", while
the latter does not, causing the address to fail completely.

In earlier versions of Exim "fail_soft" and "fail_hard" were used
instead of "pass" and "fail". They will remain as synonyms for some
time.

This option applies only to a definite `does not exist' state; if a
host lookup gets a temporary error, delivery is deferred unless the
generic "pass_on_timeout" option is set.


File: exim.info,  Node: hosts_randomize (domainlist),  Next: modemask (domainlist),  Prev: host_find_failed (domainlist),  Up: The domainlist router

hosts_randomize (domainlist) _option_
-------------------------------------

Type: boolean
Default: false

If this option is set, the order of the items in a host list in a
routing rule is randomized each time it is used. This can be used to do
crude load sharing.  However, there is a complication when a message
has more than one address that is routed by the same rule. Without
randomization, each such address ends up with an identical host list,
and so they are all eligible for batching and sending in a single SMTP
transaction. When the host order is randomized, the addresses won't all
end up with the same host list, and so they will not be batched in the
same way.

If there are only two hosts in the list, this probably doesn't matter
too much, because, on average, 50% of addresses will have them one way
round, and 50% the other, so you just get two SMTP calls instead of
one, however many addresses there are. With more than two hosts,
however, the number of permutations increases very rapidly, leading to
very many more SMTP calls being made. The way to solve this problem is
to put a single, dummy host in the routing rule, and route the
addresses to a special "smtp" transport, which has "hosts",
"hosts_randomize", and "hosts_override" set. Now all the addresses can
be batched up and sent to the transport together.


File: exim.info,  Node: modemask (domainlist),  Next: owners (domainlist),  Prev: hosts_randomize (domainlist),  Up: The domainlist router

modemask (domainlist) _option_
------------------------------

Type: octal integer
Default: 022

This specifies mode bits which must not be set for the route file.  If
they are set, delivery is deferred and the message is frozen.


File: exim.info,  Node: owners (domainlist),  Next: owngroups (domainlist),  Prev: modemask (domainlist),  Up: The domainlist router

owners (domainlist) _option_
----------------------------

Type: string list
Default: unset

This specifies a list of permitted owners for the route file. If it is
unset, no check on the ownership is done. If the file is not owned by a
user in the list, delivery is deferred and the message is frozen.


File: exim.info,  Node: owngroups (domainlist),  Next: qualify_single (domainlist),  Prev: owners (domainlist),  Up: The domainlist router

owngroups (domainlist) _option_
-------------------------------

Type: string list
Default: unset

This specifies a list of permitted groups for the route file. If it is
unset, no check on the file's group is done. If the file's group is not
in the list, delivery is deferred and the message is frozen.


File: exim.info,  Node: qualify_single (domainlist),  Next: route_file (domainlist),  Prev: owngroups (domainlist),  Up: The domainlist router

qualify_single (domainlist) _option_
------------------------------------

Type: boolean
Default: true

For any domain that is looked up in the DNS, the resolver option that
causes it to qualify single-component names with the default domain
(RES_DEFNAMES) is set. For example, on a machine called
"dictionary.ref.book", looking up the domain "thesaurus" would cause
the name "thesaurus.ref.book" to be looked up.


File: exim.info,  Node: route_file (domainlist),  Next: route_list (domainlist),  Prev: qualify_single (domainlist),  Up: The domainlist router

route_file (domainlist) _option_
--------------------------------

Type: string, expanded
Default: unset

If this option is set, "search_type" must be set to one of the
single-key lookup types, and "route_query" must not be set. See chapter
"File and database lookups" for details of file and database lookups.
The domain being routed is used as the key for the lookup, and the
resulting data must be a routing rule, in the form described below. The
file name is expanded before use.


File: exim.info,  Node: route_list (domainlist),  Next: route_queries (domainlist),  Prev: route_file (domainlist),  Up: The domainlist router

route_list (domainlist) _option_
--------------------------------

Type: string list, semicolon-separated
Default: unset

This string is a list of routing rules, in the form defined below. Note
that, unlike most string lists, the items are separated by semicolons.
This is so that they may contain colon-separated host lists. The list
is not expanded as a whole, but host lists within it are expanded
during processing.


File: exim.info,  Node: route_queries (domainlist),  Next: route_query (domainlist),  Prev: route_list (domainlist),  Up: The domainlist router

route_queries (domainlist) _option_
-----------------------------------

Type: string, expanded
Default: unset

This option is an alternative to "route_query"; the two options are
mutually exclusive. The difference is that "route_queries" contains a
colon-separated list of queries, which are tried in order until one
succeeds or defers, or all fail. Any colon characters actually required
in an individual query must be doubled, in order that they not be
treated as query separators.


File: exim.info,  Node: route_query (domainlist),  Next: search_parents (domainlist),  Prev: route_queries (domainlist),  Up: The domainlist router

route_query (domainlist) _option_
---------------------------------

Type: string, expanded
Default: unset

If this option is set, "search_type" must be set to a query-style
lookup type, and "route_file" must not be set. See chapter "File and
database lookups" for details of file and database lookups. The query
is expanded before use, and the expansion variable $domain contains the
domain being routed. The data returned from the lookup must be a
routing rule, in the form described below.


File: exim.info,  Node: search_parents (domainlist),  Next: search_type (domainlist),  Prev: route_query (domainlist),  Up: The domainlist router

search_parents (domainlist) _option_
------------------------------------

Type: boolean
Default: false

For any domain that is looked up in the DNS, the resolver option that
causes it to search parent domains (RES_DNSRCH) is set if this option
is true. This is different from the "qualify_single" option in that it
applies to domains containing dots. For example, on a machine in the
"fict.book" domain, when looking up "teaparty.wonderland" initially
fails, the resolver automatically tries "teaparty.wonderland.fict.book"
if this option is set.


File: exim.info,  Node: search_type (domainlist),  Next: Routing rules,  Prev: search_parents (domainlist),  Up: The domainlist router

search_type (domainlist) _option_
---------------------------------

Type: string
Default: unset

This option is mandatory when "route_file", "route_query", or
"route_queries" is specified. It must be set to one of the supported
search types (for example, "lsearch"). See chapter "File and database
lookups".

For single-file lookups, the name may be preceded by `partial-',
indicating a simple wildcard file lookup that works as follows:

  1. Exim first tries to look up the domain exactly as given.

  2. If that fails, it adds `*.' on the front of the domain, and looks
     that up.

  3. If that fails, it replaces the first component of the domain with
     `*' and tries that, and continues chopping off components in this
     way until either the lookup succeeds, or there are fewer than two
     non-* components left.

Thus, for example, if you put an entry keyed by `*.austen.fict.film' in
your database, that entry will be used for

  1. "austen.fict.film" by rule (b) above, having failed on rule (a).
     (If you are worried about the resource waste implied by this, you
     can always add an entry for "austen.fict.film" as well.)

  2. "emma.austen.fict.film" at the first attempt in rule (c), having
     failed on rules (a) and (b).

A domain such as `jane.fict.film' will fail, having tried 3 lookups:
`jane.fict.film', `*.jane.fict.film', `*.fict.film', but it won't waste
effort looking up `*.film' because that has only one non-* component. In
fact, the minimum number of components can be altered by including a
number immediately before the hyphen. For example, `partial4-dbm'
specifies a minimum of four non-* components.


File: exim.info,  Node: Routing rules,  Next: Host list format,  Prev: search_type (domainlist),  Up: The domainlist router

Routing rules
=============

Routing rules specified in "route_list" are scanned before "route_file",
"route_query" or "route_queries" are used. The contents of "route_list"
is a string consisting of a sequence of routing rules, separated by
semicolons. If a semicolon is needed in a rule, it can be entered as
two semicolons. Empty rules are ignored. The format of each rule is

     <domain pattern>  <host list>  <options>

The following example contains a simple domain pattern and just one
rule:

     route_list = dict.ref.book mail-1.ref.book:mail-2.ref.book byname

The three parts of a rule are separated by white space. Each rule in a
"route_list" must start with a single domain pattern, which is the only
mandatory item in the rule. The pattern is in the same format as one
item in a domain list (see section "Domain lists" in chapter "The Exim
configuration file"), that is, it may be wildcarded or a regular
expression, or a file or database lookup (with semicolons doubled,
because of the use of semicolon as a separator in a "route_list").  The
rules in "route_list" are searched in order until one of the patterns
matches the domain that is being routed. The host list and options are
then used as described below.

If no rule in "route_list" matches the domain, it is used as the key for
a lookup of the type specified by "search_type", using "route_file",
"route_query", or "route_queries", as appropriate. The data returned
from a successful lookup must be a string containing a host list and
options, separated by white space. For example, a line in a linearly
searched route file might be:

     dict.ref.book:  mail-1.ref.book:mail-2.ref.book  byname

Note that there are two different uses of the colon character in this
line. The first one is the delimiter of the key in the file, while the
second is the normal list delimiter in the host list, which in this
example consists of two host names. As both the host list and the
options are not compulsory in a rule, the data returned from a lookup
can legitimately be an empty string in some circumstances (see
Application of routing rules below).

If the domain does not match anything in "route_list" and looking it up
using "route_file", "route_query" or "route_queries" also fails, the
router declines to handle the address, and it gets passed on to the
next router, unless "no_more" is set.


File: exim.info,  Node: Host list format,  Next: Options format,  Prev: Routing rules,  Up: The domainlist router

Host list format
================

If a host list is present in the rule which matches the domain, it is
expanded before use.  If the pattern that matched the domain was a
lookup item, the data that was looked up is available in the expansion
variable $value.

The result of the expansion must be a colon-separated list of host
names and/or IP addresses. Some string expansion items may contain
white space, and if this is the case, the host list must be enclosed in
single or double quotes, because otherwise white space terminates it.
The numeric expansion variables are available during host list
expansion. These are mainly used when the domain is matched against a
regular expression domain pattern in a "route_list" string, but $1 is
also set when partial matching is done in a file lookup, and $0 is
always set to the entire domain.

The value of $domain is the original domain for the address. This may
differ from $0 if the address has been processed by a previous
"domainlist" router which passed on a different routing domain.

If the expansion of the host list is forced to fail (by using the
`fail' item in a conditional construction), the router just declines to
handle the address, and (unless "no_more" is set) it gets passed on to
the next router. If expansion fails for some other reason, the message
is frozen, since this is considered to be a configuration error.


File: exim.info,  Node: Options format,  Next: Application of routing rules,  Prev: Host list format,  Up: The domainlist router

Options format
==============

Options can be present only if there is a host list. They are a
sequence of words, but in practice no more than two are ever present.
One of the words can be the name of one of the configured transports,
and this overrides the "transport" option on the router for this
particular routing rule only.  The other word (if present) specifies
how the IP addresses of the hosts in the host list are to be found:

   * "byname": use "gethostbyname()", or use literal IP addresses if
     present.  Literal IP addresses are written without any surrounding
     square brackets.

   * "bydns": use the DNS, doing the full MX and A record processing.

   * "bydns_a": look up A records for the host(s) in the DNS; fail if
     there are none.

   * "bydns_mx": look up MX records for the host(s) in the DNS; fail if
     there are none.

The "qualify_single" and "search_parents" options apply to any DNS
lookups that are done.  If no IP address for a host can be found, what
happens is controlled by the "host_find_failed" option.


File: exim.info,  Node: Application of routing rules,  Next: Domainlist examples,  Prev: Options format,  Up: The domainlist router

Application of routing rules
============================

When a rule has been found that matches the current domain, either by
matching one of the rules in "route_list", or by a successful lookup in
"route_file" or using "route_query" or "route_queries", the host list
and options are used in a number of different ways, depending on which
are present and on whether a transport has been specified.

   * If there is no host list (and therefore necessarily no options
     either), a local transport (that is, not an SMTP transport) must
     be specified for the router via the generic "transport" option,
     unless the driver is being used only for verification
     ("verify_only" is set).  In this case, if there is no transport
     and no host list, the address is taken as verified. Otherwise,
     failure to specify a local transport in the absence of a host list
     is a configuration error. The address is routed to the transport.
     In all other cases, a host list must be provided.

   * If there is a host list, and a local transport is specified either
     by the generic "transport" option, or by an option item in the
     rule, the host list must contain just a single host name which is
     passed to the transport in the $host variable. Any "byxxx" options
     are ignored.

   * If no "byxxx" option is present, any remote transport setting is
     ignored, and there must be just one name in the host list. The
     address is passed on to the next router, overriding "no_more",
     with the domain being routed being replaced by the name from the
     host list.  However if the expansion variable $domain is used in
     any subsequent router, it still refers to the original domain.

   * Otherwise, a remote (that is, SMTP) transport must be specified,
     unless the driver is being used only for verification
     ("verify_only" is set), or the routing rule specifies the local
     host, and the generic "self" option is set to something other than
     `send'.

     The transport is specified either via the generic "transport"
     option or by a transport name as an option setting, and there may
     be many hosts in the list.  Their IP addresses are looked up
     according to the "byxxx" option. If any of them are found to be
     the local host, that one and all those that follow it are
     discarded. If the first host is found to be the local host, the
     generic "self" option specifies what happens. Otherwise, the
     address is passed to the specified transport, along with the
     ordered list of hosts. The transport will try delivering to each
     host in turn, until one accepts the message.

     If the attempt to look up an IP address for a host fails, the
     "host_find_failed" option controls what happens.

The various different possibilities for configuring the "domainlist"
router make it possible to use it for a number of different routing
requirements, as shown in the examples in the next section.


File: exim.info,  Node: Domainlist examples,  Prev: Application of routing rules,  Up: The domainlist router

Domainlist examples
===================

In some of the examples that follow, the presence of the "remote_smtp"
transport, as defined in the default configuration file, is assumed.

   * Routing to a gateway to another mail environment can be set up
     using a wildcarded domain pattern that matches some pseudo
     top-level domain. For example, to route certain addresses to UUCP
     and Bitnet gateways:

          uucp_bitnet:
            driver = domainlist
            route_list = *.uucp   uugateway.fict.book; \
                         *.bitnet bngateway.ref.book

     The two rules match domains ending in ".uucp" and ".bitnet"
     respectively, and because no options or transport are specified in
     either case, the name of the appropriate gateway domain is taken
     from the host list and passed to subsequent routers for further
     routing. So, for example, mail addressed to "user@faraway.uucp" is
     routed by applying subsequent routers to the domain
     "uugateway.fict.book" to determine where to send it.

     If there are two hosts servicing one of these domains and they are
     not connected to a single domain name (by MX records for example),
     you may want to quote two names in the host list portion of a
     rule. In this case, you have to specify one of the "byxxx"
     options, to get the names looked up by "domainlist", since it can
     pass on only a single domain name to other routers.  A transport
     must also be provided:

          uucp:
            driver = domainlist
            transport = remote_smtp
            route_list = \
              *.uucp uugate1.fict.book:uugate2.fict.book byname

     In this case, no further routers are called.

   * A host that is itself a gateway can `deliver' messages to pipes or
     into files in batched SMTP format for onward transportation by
     some other means. In this case, the route list entry can be as
     simple as a single domain name in a configuration like this:

          route_append:
            driver = domainlist
            transport = batchsmtp_appendfile
            route_list = gated.domain

     though often a pattern is used to pick up more than one domain. If
     there are several domains or groups of domains with different
     transport requirements, different transports can be listed in the
     routing information:

          route_append:
            driver = domainlist
            route_list = \
              *.gated.domain1  $domain  batch_appendfile; \
              *.gated.domain2  \
                ${lookup{$domain}dbm{/domain2/hosts}{$value}fail} \
                batch_pipe

     The first of these just passes the domain in the $host variable,
     which doesn't achieve much (since it is also in $domain) but the
     second does a file lookup to find a value to pass, causing the
     router to decline to handle the address if the lookup fails.

   * Routing mail directly to UUCP software is a specific case of the
     use of "domainlist" in a gateway to another mail environment. This
     is an example of one way it can be done, taken from a real
     configuration:

          # Transport
          uucp:
            driver = pipe
            user = nobody
            command = /usr/local/bin/uux -r - \
              ${substr_-5:$host}!rmail ${local_part}
            return_fail_output = true


          # Router
          uucphost:
            transport = uucp
            driver = domainlist
            route_file = /usr/local/exim/uucphosts
            search_type = lsearch

     The file "/usr/local/exim/uucphosts" contains entries like

          darksite.ethereal.ru:           darksite.UUCP

     It can be set up more simply without adding and removing `.UUCP'
     but this way makes clear the distinction between the domain name
     "darksite.ethereal.ru" and the UUCP host name "darksite".

   * A "mail hub" is a machine which receives mail for a number of
     domains via MX records in the DNS and delivers it via its own
     private routing mechanism. Often the final destinations are behind
     a firewall, with the mail hub being the one machine that can
     connect to machines both inside and outside the firewall. The
     "domainlist" router can be set up for this kind of purpose:

          through_firewall:
            driver = domainlist
            transport = remote_smtp
            route_file = /internal/host/routes
            search_type = lsearch

     For a small number of cases, the routing could be inline, using the
     "route_list" option, but for a larger number a file lookup would
     be easier to manage, and the file containing the internal routing
     might contain lines like this:

          dict.ref.book:  mail-1.ref.book:mail-2.ref.book  byname

     The DNS would be set up with an MX record for "dict.ref.book"
     pointing to the mail hub, which would then then forward mail for
     "dict.ref.book" to one of the two specified machines, looking up
     their addresses using "gethostbyname()".

     If the domain names are in fact the names of the machines to which
     the mail is to be sent by the mail hub, the configuration can be
     quite simple. For example,

          hub_route:
            driver = domainlist
            transport = remote_smtp
            route_list = *.rhodes.tvs  $domain  byname

     This configuration routes domains that match `*.rhodes.tvs' by
     calling "gethostbyname()" on the domain that matched. A similar
     approach can be taken if the host name can be obtained from the
     domain name by simple manipulation that the expansion facilities
     can handle.

   * The "domainlist" router can also be used to forward all non-local
     mail to a "smart host" by using a configuration like

          smart_route:
            driver = domainlist
            transport = remote_smtp
            route_list = *  smarthost.ref.book  bydns_a

     which causes all messages containing remote addresses to be sent
     to the single host "smarthost.ref.book", whose address (in this
     example) is obtained from its DNS address record. If a
     colon-separated list of smart hosts is given, they are tried in
     order. A router like this should be the last one in the
     configuration file, since it will route any domain whatsoever.

   * A "domainlist" router can be used to force success or failure on
     verification of remote addresses by setting "verify_only" (and
     "verify_sender" or "verify_recipient" if required). If failure is
     wanted, set "fail_verify". No transports or hosts need be defined.


File: exim.info,  Node: The ipliteral router,  Next: The iplookup router,  Prev: The domainlist router,  Up: Top

The ipliteral router
********************

This router succeeds if the `domain' being routed takes the form of an
RFC 822 domain literal, that is, an IP address in dotted-quad notation
enclosed in square brackets. For example, this router handles the
address

     root@[192.168.1.1]

by setting up delivery to the host with that IP address. If an IP
literal turns out to refer to the local host, the generic "self" option
determines what happens. The RFCs require support for domain literals,
though it seems anachronistic in today's Internet. There are no private
options for this router; a transport must be set using the generic
"transport" option.


File: exim.info,  Node: The iplookup router,  Next: The lookuphost router,  Prev: The ipliteral router,  Up: Top

The iplookup router
*******************

The "iplookup" router was written to fulfil a specific requirement in
Cambridge. For this reason, it is not included in the binary of Exim by
default. If you want to include it, you must set

     ROUTER_IPLOOKUP=yes

in your `Local/Makefile' configuration file.

The "iplookup" router routes an address by sending it over a TCP or UDP
connection to one or more specific hosts. The host can then return the
same or a different address - in effect rewriting the recipient address
in the message's envelope. If this process fails, the address can be
passed on to other routers, or delivery can be deferred.

Background, for those that are interested: We have an Oracle database
of all Cambridge users, and one of the bits of data it maintains for
each user is where to send mail addressed to "<user>@cam.ac.uk". The MX
records for "cam.ac.uk" point to a central machine that has a large
alias list that is abstracted from the database. Mail from outside is
switched by this system, and originally internal mail was also done
this way. However, this resulted in a fair number of messages
travelling from some of our larger systems to the switch and back
again. The Oracle machine now runs a UDP service that can be called by
the "iplookup" router in Exim to find out where "<user>@cam.ac.uk"
addresses really have to go; this saves passing through the central
switch, and in many cases saves doing any remote delivery at all.

Since "iplookup" is just a rewriting router, a transport must not be
specified for it.



* Menu:

* hosts (iplookup)::
* optional (iplookup)::
* port (iplookup)::
* protocol (iplookup)::
* query (iplookup)::
* reroute (iplookup)::
* response_pattern (iplookup)::
* service (iplookup)::
* timeout (iplookup)::


File: exim.info,  Node: hosts (iplookup),  Next: optional (iplookup),  Prev: The iplookup router,  Up: The iplookup router

hosts (iplookup) _option_
-------------------------

Type: string
Default: unset

This option must be supplied. Its value is a colon-separated list of
host names. The hosts are looked up using "gethostbyname()" and are
tried in order until one responds to the query.


File: exim.info,  Node: optional (iplookup),  Next: port (iplookup),  Prev: hosts (iplookup),  Up: The iplookup router

optional (iplookup) _option_
----------------------------

Type: boolean
Default: false

If "optional" is true, if no response is obtained from any host, the
address is passed on to the next router, overriding "no_more".  If
"optional" is false, delivery to this address is deferred.


File: exim.info,  Node: port (iplookup),  Next: protocol (iplookup),  Prev: optional (iplookup),  Up: The iplookup router

port (iplookup) _option_
------------------------

Type: integer
Default: 0

This option must be supplied. It specifies the port number for the TCP
or UDP call.


File: exim.info,  Node: protocol (iplookup),  Next: query (iplookup),  Prev: port (iplookup),  Up: The iplookup router

protocol (iplookup) _option_
----------------------------

Type: string
Default: "udp"

This option can be set to `udp' or `tcp' to specify which of the two
protocols is to be used.


File: exim.info,  Node: query (iplookup),  Next: reroute (iplookup),  Prev: protocol (iplookup),  Up: The iplookup router

query (iplookup) _option_
-------------------------

Type: string, expanded
Default: "${local_part}@${domain} ${local_part}@${domain}"

This defines the content of the query that is sent to the remote hosts.
The repetition serves as a way of checking that a response is to the
correct query in the default case (see "response_pattern" below).


File: exim.info,  Node: reroute (iplookup),  Next: response_pattern (iplookup),  Prev: query (iplookup),  Up: The iplookup router

reroute (iplookup) _option_
---------------------------

Type: string, expanded
Default: unset

If this option is not set, the rerouted address is precisely the byte
string returned by the remote host, up to the first white space, if
any. If set, the string is expanded to form the rerouted address. It
can include parts matched in the response by "response_pattern" by
means of numeric variables such as $1, $2, etc. The variable $0 refers
to the entire input string, whether or not a pattern is in use. In all
cases, the rerouted address must end up in the form
<local_part>@<domain>.


File: exim.info,  Node: response_pattern (iplookup),  Next: service (iplookup),  Prev: reroute (iplookup),  Up: The iplookup router

response_pattern (iplookup) _option_
------------------------------------

Type: string
Default: unset

This option can be set to a regular expression that is applied to the
string returned from the remote host. If the pattern does not match the
response, the router declines. If "response_pattern" is not set, no
checking of the response is done, unless the query was defaulted, in
which case there is a check that the text returned after the first
white space is the original address. This checks that the answer that
has been received is in response to the correct question.  For example,
if the response is just a new domain, the following could be used:

     response_pattern = ^([^@]+)$
     reroute = $local_part@$1


File: exim.info,  Node: service (iplookup),  Next: timeout (iplookup),  Prev: response_pattern (iplookup),  Up: The iplookup router

service (iplookup) _option_
---------------------------

Type: integer
Default: 0

This is an alternative name for the "port" option.


File: exim.info,  Node: timeout (iplookup),  Prev: service (iplookup),  Up: The iplookup router

timeout (iplookup) _option_
---------------------------

Type: time
Default: 5s

This specifies the amount of time to wait for a response from the remote
machine.  The same timeout is used for the "connect()" function for a
TCP call. It does not apply to UDP.


File: exim.info,  Node: The lookuphost router,  Next: The queryprogram router,  Prev: The iplookup router,  Up: Top

The lookuphost router
*********************

The "lookuphost" router looks up the hosts that handle mail for the
given domain either via the "gethostbyname()" function, or by using the
DNS directly.  A transport must always be set for this router, unless
"verify_only" is set.

When the DNS is used, MX records are looked up first, followed by
address records if no MX records are found, unless the domain matches
"mx_domains". MX records of equal priority are sorted by Exim into a
random order.  Unless they have the highest priority (lowest MX value),
MX records that point to the local host, or to any host name that
matches "hosts_treat_as_local", are discarded, together with any other
MX records of equal or lower priority.

If the host pointed to by the highest priority MX record or the host
looked up by "gethostbyname()" is the local host, or matches
"hosts_treat_as_local", then what happens is controlled by the generic
"self" option.



* Menu:

* check_secondary_mx (lookuphost)::
* gethostbyname (lookuphost)::
* mx_domains (lookuphost)::
* qualify_single (lookuphost)::
* rewrite_headers (lookuphost)::
* search_parents (lookuphost)::
* widen_domains (lookuphost)::


File: exim.info,  Node: check_secondary_mx (lookuphost),  Next: gethostbyname (lookuphost),  Prev: The lookuphost router,  Up: The lookuphost router

check_secondary_mx (lookuphost) _option_
----------------------------------------

Type: boolean
Default: false

If this option is set, the router declines unless the local host is
found in (and removed from) the list of hosts obtained by MX lookup.
This can be used to process domains for which the local host is a
secondary mail exchanger differently to other domains.


File: exim.info,  Node: gethostbyname (lookuphost),  Next: mx_domains (lookuphost),  Prev: check_secondary_mx (lookuphost),  Up: The lookuphost router

gethostbyname (lookuphost) _option_
-----------------------------------

Type: boolean
Default: false

If this is true, the "gethostbyname()" function is used and the options
relating to the DNS are ignored. Otherwise, the name is looked up
directly in the DNS. Of course, "gethostbyname()" may do its own DNS
lookup for an A record (no MX processing is involved), but it may also
access other sources of information such as "/etc/hosts".

When Exim is compiled with IPv6 support, if a host that is looked up in
the DNS has both A and AAAA or A6 records, all the addresses are used.


File: exim.info,  Node: mx_domains (lookuphost),  Next: qualify_single (lookuphost),  Prev: gethostbyname (lookuphost),  Up: The lookuphost router

mx_domains (lookuphost) _option_
--------------------------------

Type: domain list
Default: unset

This option applies to domains that are looked up directly in the DNS
("gethostbyname" is not set). A domain which matches "mx_domains" is
required to have an MX record in order to be recognised. For example,
if all the mail hosts in "fict.book" are known to have MX records,
except for those in "discworld.fict.book", options of the form

     mx_domains = ! *.discworld.fict.book : *.fict.book

could be used. This would cause messages addressed to a machine that
matched the option but had only an A record to be bounced immediately
instead of sitting on the queue until the delivery timed out.


File: exim.info,  Node: qualify_single (lookuphost),  Next: rewrite_headers (lookuphost),  Prev: mx_domains (lookuphost),  Up: The lookuphost router

qualify_single (lookuphost) _option_
------------------------------------

Type: boolean
Default: true

If domains are being looked up in the DNS ("gethostbyname" is false),
the resolver option that causes it to qualify single-component names
with the default domain (RES_DEFNAMES) is set. For example, on a
machine called "dictionary.ref.book", looking up the domain "thesaurus"
would cause the name "thesaurus.ref.book" to be looked up internally in
the resolver. Exim itself still looks up the single name.


File: exim.info,  Node: rewrite_headers (lookuphost),  Next: search_parents (lookuphost),  Prev: qualify_single (lookuphost),  Up: The lookuphost router

rewrite_headers (lookuphost) _option_
-------------------------------------

Type: boolean
Default: true

An abbreviated name may be expanded to its full form by both
"gethostbyname()" or by DNS lookup, or as a result of the
"widen_domains" option. For example, if an address is specified as
"dormouse@teaparty", the domain might get expanded to
"teaparty.wonderland.fict.book". If this option is true, all
occurrences of the abbreviated name in the headers of the message are
rewritten with the full name. This option should be turned off only
when it is known that no message is ever going to be sent outside an
environment where the abbreviation makes sense.

When an MX record is looked up in the DNS and matches a wildcard record,
nameservers normally return a record containing the name that has been
looked up, making it impossible to detect whether a wildcard was
present or not.  However, some nameservers have recently been seen to
return the wildcard entry.  If the name returned by a DNS lookup begins
with an asterisk, it is not used for header rewriting.


File: exim.info,  Node: search_parents (lookuphost),  Next: widen_domains (lookuphost),  Prev: rewrite_headers (lookuphost),  Up: The lookuphost router

search_parents (lookuphost) _option_
------------------------------------

Type: boolean
Default: false

If domains are being looked up in the DNS ("gethostbyname" is false),
the resolver option that causes it to search parent domains
(RES_DNSRCH) is set if this option is true. This is different from the
"qualify_single" option in that it applies to domains containing dots.
For example, on a machine in the "fict.book" domain, when looking up
"teaparty.wonderland" initially fails, the resolver automatically tries
"teaparty.wonderland.fict.book" if this option is set. The default
setting of this option used to be true, but this causes problems in
domains that have a wildcard MX record, because any domain that does
not have its own MX record then matches the local wildcard. The default
was changed to false in Exim 1.80.


File: exim.info,  Node: widen_domains (lookuphost),  Prev: search_parents (lookuphost),  Up: The lookuphost router

widen_domains (lookuphost) _option_
-----------------------------------

Type: string list
Default: unset

If a lookup fails and this option is set, each of its strings in turn
is added onto the end of the domain, and the lookup is tried again. For
example, if

     widen_domains = fict.book:ref.book

is set and a lookup of "klingon.dictionary" fails,
"klingon.dictionary.fict.book" is looked up, and if this fails,
"klingon.dictionary.ref.book" is tried. This option applies to lookups
using "gethostbyname()" as well as to DNS lookups. Note that when the
DNS is being used for lookups, the "qualify_single" and
"search_parents" options cause some widening to be undertaken inside
the DNS resolver.


File: exim.info,  Node: The queryprogram router,  Next: Retry configuration,  Prev: The lookuphost router,  Up: Top

The queryprogram router
***********************

The "queryprogram" router routes a domain by running an external
command and acting on its output. This is an expensive way to route,
and is intended mainly for use in lightly-loaded systems, or for
performing experiments.  However, if it is possible to use the
"domains", "local_parts" or "condition" generic options to skip this
router for most addresses, it could sensibly be used in special cases.
There are the following private options:



* Menu:

* command (queryprogram)::
* command_group (queryprogram)::
* command_user (queryprogram)::
* current_directory (queryprogram)::
* timeout (queryprogram)::
* The queryprogram router (continued)::


File: exim.info,  Node: command (queryprogram),  Next: command_group (queryprogram),  Prev: The queryprogram router,  Up: The queryprogram router

command (queryprogram) _option_
-------------------------------

Type: string, expanded
Default: unset

This option must be set, and must start with a slash character. It
specifies the command that is to be run. It is expanded before use.
Failure to expand causes delivery to be deferred and the message to be
frozen.


File: exim.info,  Node: command_group (queryprogram),  Next: command_user (queryprogram),  Prev: command (queryprogram),  Up: The queryprogram router

command_group (queryprogram) _option_
-------------------------------------

Type: string
Default: unset

This option specifies a gid to be set when running the command. If it
begins with a digit it is interpreted as the numerical value of the
gid. Otherwise it is looked up using "getgrnam()".


File: exim.info,  Node: command_user (queryprogram),  Next: current_directory (queryprogram),  Prev: command_group (queryprogram),  Up: The queryprogram router

command_user (queryprogram) _option_
------------------------------------

Type: string
Default: unset

This option specifies the uid which is set when running the command.
If it begins with a digit it is interpreted as the numerical value of
the uid.  Otherwise, it is looked up using "getpwnam()" to obtain a
value for the uid and, if "command_group" is not set, a value for the
gid also.


File: exim.info,  Node: current_directory (queryprogram),  Next: timeout (queryprogram),  Prev: command_user (queryprogram),  Up: The queryprogram router

current_directory (queryprogram) _option_
-----------------------------------------

Type: string
Default: unset

This option specifies an absolute path which is made the current
directory before running the command. If it is not set, `/' is used.


File: exim.info,  Node: timeout (queryprogram),  Next: The queryprogram router (continued),  Prev: current_directory (queryprogram),  Up: The queryprogram router

timeout (queryprogram) _option_
-------------------------------

Type: time
Default: 1h

If the command does not complete within the timeout period, its process
group is killed and the message gets frozen. A value of zero time
specifies no timeout.


File: exim.info,  Node: The queryprogram router (continued),  Prev: timeout (queryprogram),  Up: The queryprogram router

If "command_user" is not specified, the command is run as `nobody'. If
the main configuration has not defined a user and group for `nobody',
it is looked up using "getpwnam()". If this fails, delivery is deferred
and the message is frozen.

In previous versions of Exim the "command_group" and "command_user"
options were called "group" and "user". Their names were changed when
"group" and "user" became generic router options.

The standard output of the command is connected to a pipe, which is
read when the command terminates. It should consist of a single line of
output, containing up to five fields, separated by white space. The
first field is one of the following words:

   * OK: routing succeeded; the remaining fields specify what to do.

   * DECLINE: the router declines; pass the address to the next router,
     unless "no_more" is set. (Formerly, FAIL was used for this; it
     remains for a while as a synonym.)

   * FORCEFAIL: routing failed; do not pass the address to any more
     routers.

   * DEFER: routing could not be completed at this time; try again
     later.

   * ERROR: some disastrous error occurred; freeze the message.

When the first word is not OK, the remainder of the line is an error
message explaining what went wrong. For example:

     FAIL  queryprogram cannot route to unseen.discworld.fict.book

Otherwise, the line must be formatted as follows:

     OK <transport name> <new domain> <option> <arbitrary text>

The second field is the name of a transport instance, or a plus
character, which means that the transport specified for the router
using the generic "transport" option is to be used, if set.

If the third field is not empty or a single plus character, it is a new
domain name to replace the current one. If a transport is specified and
the fourth field is not empty or a plus character, it specifies the
method of looking up the new name. This can be one of the words
`byname', `bydns', `bydns_a', or `bydns_mx'. For example,

     OK  smtp  gate.star.fict.book  bydns_a

causes the message to be sent using the "smtp" transport to the host
"gate.star.fict.book", whose address is looked up as a DNS address
record.  If the host turns out to be the local host, what happens is
controlled by the generic "self" option.

The fifth field, if present, is made available to the transport via the
expansion variable $route_option. For example, a line such as

     OK special + + /computed/filename

sends the message to the "special" transport, which can use
$route_option in its configuration to access the text
`/computed/filename'.

The fourth and fifth fields are ignored and the new domain name (if
any) is passed to the next router if no transport is specified in the
response line (that is, a plus character is given) and the generic
"transport" option is also unset.  This counts as an explicitly
configured `pass', and overrides "no_more".


File: exim.info,  Node: Retry configuration,  Next: Address rewriting,  Prev: The queryprogram router,  Up: Top

Retry configuration
*******************

The fifth part of the configuration file contains a list of retry rules
which control how often Exim tries to deliver messages that cannot be
delivered at the first attempt. If there are no retry rules, Exim gives
up after the first failure. The -brt command line option can be used to
test which retry rule will be used for a given address or domain.

The most common cause of retries is temporary failure to deliver to a
remote host. Exim's retry processing in this case is applied on a
per-host (strictly, per IP address) basis, not on a per-message basis.
Thus, if one message has recently been delayed, a new message to the
same host does not immediately get tried, but waits for the host's
retry time to arrive. If the value of "log_level" is greater than 4,
the message `retry time not reached' is written to the main log
whenever a delivery is skipped for this reason. Section "Errors in
outgoing SMTP" in chapter "SMTP processing" contains more details of the
handling of errors during remote deliveries.

Retry processing applies to directing and routing as well as to
delivering, except as covered in the next paragraph. The retry rules do
not distinguish between these three actions, so it is not possible, for
example, to specify different behaviour for failures to route the
domain "snark.fict.book" and failures to deliver to the host
"snark.fict.book". I didn't think anyone would ever need this added
complication, so did not implement it.  However, although they share
the same retry rule, the actual retry times for routing, directing, and
transporting a given domain are maintained independently.

When a delivery is not part of a queue run (typically an immediate
delivery on receipt of a message), the directors are always run for
local addresses, and local deliveries are always attempted, even if
retry times are set for them.  This makes for better behaviour if one
particular message is causing problems (for example, causing quota
overflow, or provoking an error in a filter file).  If such a delivery
suffers a temporary failure, the retry data gets updated as normal, and
subsequent delivery attempts from queue runs occur only when the retry
time for the local address is reached.



* Menu:

* Retry rules::
* Retry rule examples::
* Timeout of retry data::
* Long-term failures::
* Ultimate address timeout::


File: exim.info,  Node: Retry rules,  Next: Retry rule examples,  Prev: Retry configuration,  Up: Retry configuration

Retry rules
===========

Each retry rule occupies one line and consists of three parts,
separated by white space: a pattern, an error name, and a list of retry
parameters. The rules are searched in order until one is found whose
pattern matches the failing host or address.

The pattern may be a complete address ("local_part@domain"), a plain
domain, a wildcarded domain (that is, starting with an asterisk), a
domain lookup (as in a domain list), or a regular expression. The first
form must be used with local domains only; in this case the local part
may begin with an asterisk.

After a directing or local delivery failure, regular expressions and
patterns containing local parts are normally matched against the
complete address ("local_part@domain"). However, if there is no local
part in a pattern that is not a regular expression, the local part of
the address isn't used in the matching. Thus an entry such as

     lookingglass.fict.book        *  F,24h,30m;

matches any address whose domain is "lookingglass.fict.book", whether
this is a local or a remote domain, whereas

     alice@lookingglass.fict.book  *  F,24h,30m;

can be used only if "lookingglass.fict.book" is a local domain. It
applies to temporary failures involving the local part "alice", but not
to any other local parts.

If a local delivery is being used to collect messages for onward
transmission by some other means (for example, as batched SMTP), a
temporary failure may not be dependent on the local part at all. Both
the "appendfile" and "pipe" transports have an option called
"retry_use_local_part" which can be set false in order to suppress the
inclusion of local parts when matching retry patterns for those
transport instances. When this option is set, patterns containing local
parts are skipped, and regular expressions are matched against the
domain only.

For remote domains, when looking for a retry rule after a routing
attempt has failed (for example, after a DNS timeout), each line in the
retry configuration is tested only against the domain in the address.
However, when looking for a retry rule after a remote delivery attempt
has failed (for example, a connection timeout), each line in the retry
configuration is first tested against the remote host name, and then
against the domain name in the address.  For example, if the MX records
for "a.b.c.d" are

     a.b.c.d  MX  5  x.y.z
              MX  6  p.q.r
              MX  7  m.n.o

and the retry rules are

     p.q.r    *      F,24h,30m;
     a.b.c.d  *      F,4d,45m;

then failures to deliver to host "p.q.r" use the first rule to
determine retry times, but for all the other hosts for the domain
"a.b.c.d", the second rule is used, and that rule would also be used if
routing to "a.b.c.d" suffers a temporary failure.

The second field in a retry rule is the name of a particular error, or
an asterisk, which matches any error. The errors that can be tested for
are:

   - "refused_MX": connection refused from a host obtained from an MX
     record

   - "refused_A": connection refused from a host not obtained from an
     MX record

   - "refused": any connection refusal

   - "timeout_connect": connection timed out

   - "timeout_DNS": DNS lookup timed out

   - "timeout": any timeout

   - "quota": quota exceeded in local delivery

   - "quota_<time>": quota exceeded in local delivery, and the mailbox
     has not been read for <time>.

The quota errors apply both to system-enforced quotas and to Exim's own
quota mechanism in the "appendfile" transport.  It also applies when a
local delivery is deferred because a partition is full (the ENOSPC
error).

The third field in a retry rule is a sequence of retry parameter sets,
separated by semicolons. Each set consists of

     <letter>,<cutoff time>,<arguments>

The letter identifies the algorithm for computing a new retry time; the
cutoff time is the time beyond which this algorithm no longer applies,
and the arguments vary the algorithm's action. The cutoff time is
measured from the time that the first failure for the domain (combined
with the local part if relevant) was detected, not from the time the
message was received.  The available algorithms are:

   * "F": retry at fixed intervals. There is a single time parameter
     specifying the interval.

   * "G": retry at geometrically increasing intervals. The first
     argument specifies a starting value for the interval, and the
     second a multiplier.

When computing the next retry time, the algorithm definitions are
scanned in order until one whose cutoff time has not yet passed is
reached. This is then used to compute a new retry time that is later
than the current time. In the case of fixed interval retries, this
simply means adding the interval to the current time. For geometrically
increasing intervals, retry intervals are computed from the rule's
parameters until one that is greater than the previous interval is
found. The main configuration variable "retry_interval_max" limits the
maximum interval between retries.

A single remote domain may have a number of hosts associated with it,
and each host may have more than one IP address. Retry algorithms are
selected on the basis of the domain name, but are applied to each IP
address independently. If, for example, a host has two IP addresses and
one is broken, Exim will generate retry times for it and will not try
to use it until its next retry time comes.  Thus the good IP address is
likely to be tried first most of the time.

Retry times are hints rather than promises. Exim does not make any
attempt to run deliveries exactly at the computed times. Instead, a
queue-running process starts delivery processes for delayed messages
periodically, and these attempt new deliveries only for those addresses
that have passed their next retry time.  If a new message arrives for a
deferred address, an immediate delivery attempt occurs only if the
address has passed its retry time. In the absence of new messages, the
minimum time between retries is the interval between queue-running
processes. There is not much point in setting retry times of five
minutes if your queue-runners happen only once an hour, unless there
are a significant number of incoming messages (which might be the case
on a system that is sending everything to a smart host, for example).

The data in the retry hints database can be inspected by using the
"exim_dumpdb" or "exim_fixdb" utility programs (see chapter "Exim
utilities"). The latter utility can also be used to change the data.
The "exinext" utility script can be used to find out what the next
retry times are for the hosts associated with a particular mail domain,
and also for local deliveries that have been deferred.


File: exim.info,  Node: Retry rule examples,  Next: Timeout of retry data,  Prev: Retry rules,  Up: Retry configuration

Retry rule examples
===================

Here are some example retry rules suitable for use when
"wonderland.fict.book" is a local domain:

     alice@wonderland.fict.book quota_5d  F,7d,3h
     wonderland.fict.book       quota_5d
     wonderland.fict.book       *         F,1h,15m; G,2d,1h,2;
     lookingglass.fict.book     *         F,24h,30m;
     *                          refused_A F,2h,20m;
     *                          *         F,2h,15m; G,16h,1h,1.5; F,5d,8h

The first rule sets up special handling for mail to
"alice@wonderland.fict.book" when there is an over-quota error and the
mailbox hasn't been read for at least 5 days. Retries continue every
three hours for 7 days. The second rule handles over-quota errors for
all other local parts at "wonderland.fict.book"; the absence of a local
part has the same effect as supplying `*@'. As no retry algorithms are
supplied, messages that fail are bounced immediately if the mailbox
hasn't been read for at least 5 days.

The third rule handles all other errors at "wonderland.fict.book";
retries happen every 15 minutes for an hour, then with geometrically
increasing intervals until two days have passed since a delivery first
failed. The fourth rule controls retries for the domain
"lookingglass.fict.book", whether it is local or remote, and the
remaining two rules handle all other domains, with special action for
connection refusal from hosts that were not obtained from an MX record.

The final rule in a retry configuration should always have asterisks in
the first two fields so as to provide a general catch-all for any
addresses that do not have their own special handling. This example
tries every 15 minutes for 2 hours, then with intervals starting at one
hour and increasing by a factor of 1.5 up to 16 hours, then every 8
hours up to 5 days.


File: exim.info,  Node: Timeout of retry data,  Next: Long-term failures,  Prev: Retry rule examples,  Up: Retry configuration

Timeout of retry data
=====================

Exim timestamps the data that it writes to its retry hints database.
When it consults the data during a delivery it ignores any that is
older than the value set in "retry_data_expire" (default 7 days). If,
for example, a host hasn't been tried for 7 days, Exim will try to
deliver to it immediately a message arrives, and if that fails, it will
calculate a retry time as if it were failing for the first time.

This improves the behaviour for messages routed to rarely-used hosts
such as MX backups. If such a host was down at one time, and happens to
be down again when Exim tries a month later, using the old retry data
would imply that it had been down all the time, which is not a
justified assumption.

If a host really is permanently dead, this behaviour causes a burst of
retries every now and again, but only if messages routed to it are
rare. It there is a message at least once every 7 days the retry data
never expires.


File: exim.info,  Node: Long-term failures,  Next: Ultimate address timeout,  Prev: Timeout of retry data,  Up: Retry configuration

Long-term failures
==================

Special processing happens when an address has been failing for so long
that the cutoff time for the last algorithm has been reached. This is
independent of how long any specific message has been failing; it is
the length of continuous failure for the address that counts. When this
is the case for a local delivery, or for all IP addresses associated
with a remote delivery, a subsequent delivery failure causes Exim to
give up on the address, and a delivery error message is generated. In
order to cater for new messages that may use the failing address, a
next retry time is still computed from the final algorithm, and is used
as follows:

If the delivery is a local one, one delivery attempt is always made for
any subsequent messages. If it fails, the address fails immediately. The
post-cutoff retry time is not used.

If the delivery is remote, there are two possibilities, controlled by
the "delay_after_cutoff" option of the "smtp" transport. The option is
true by default and in that case:

   - Until the post-cutoff retry time for one of the IP addresses is
     reached, any attempt to deliver to the failing address is bounced
     immediately. After that time, one new delivery attempt is made to
     those IP addresses that are past their retry times, and if that
     still fails, the address is bounced and new retry times are
     computed.

In other words, Exim delays retrying an IP address after the final
cutoff time until a new retry time is reached, and can therefore bounce
an email address without ever trying a delivery when machines have been
down for a long time.  This ensures that few resources are wasted in
repeatedly trying to deliver to a broken destination, but if it does
recover, Exim will eventually notice.

If "delay_after_cutoff" is set false, Exim behaves differently. If all
IP addresses are past their final cutoff time, Exim tries to deliver to
those IP addresses that have not been tried since the message arrived.
If there are none, or if they all fail, the address is bounced. In
other words, it does not delay when a new message arrives, but tries
the expired addresses immediately, unless they have been tried since
the message arrived. If there is a continuous stream of messages for
the failing domains, unsetting "delay_after_cutoff" means that there
will be many more attempts to deliver to failing IP addresses than when
"delay_after_cutoff" is true.


File: exim.info,  Node: Ultimate address timeout,  Prev: Long-term failures,  Up: Retry configuration

Ultimate address timeout
========================

An additional rule is needed to cope with cases where a host is
intermittently available, or when a message has some attribute that
prevents its delivery when others to the same address get through. In
this situation, because some messages are successfully delivered, the
`retry clock' for the address keeps getting restarted, and so a message
could remain on the queue for ever. To prevent this, if a message has
been on the queue for longer than the cutoff time of any applicable
retry rule for a given address, a delivery is attempted for that
address, even if it is not yet time, and if this delivery fails, the
address is timed out. A new retry time is not computed in this case, so
that other messages for the same address are considered immediately.


File: exim.info,  Node: Address rewriting,  Next: SMTP authentication,  Prev: Retry configuration,  Up: Top

Address rewriting
*****************

There are some circumstances in which Exim automatically rewrites
domains in addresses. The two most common are when an address is given
without a domain (for addresses in envelopes, this is permitted only
for locally submitted messages, or messages from hosts that match
"sender_unqualified_hosts" or "receiver_unqualified_hosts") or when an
address contains an abbreviated domain that is expanded by DNS lookup.

One situation in which Exim does not rewrite a domain is when it is the
name of a CNAME record in the DNS. The older RFCs suggest that such a
domain should be rewritten using the `canonical' name, and some MTAs do
this. The new draft RFCs do not contain this suggestion.

This chapter is about address rewriting that is explicitly specified in
the configuration.  Some people believe that configured rewriting is a
Mortal Sin. Others believe that life is not possible without it. Exim
provides the facility; you do not have to use it.

In general, rewriting addresses from your own system or domain has some
legitimacy. Rewriting other addresses should be done only with great
care and in special circumstances. The author of Exim believes that
rewriting should be used sparingly, and mainly for `regularizing'
addresses in your own domains.  Although it can be used as a routing
tool, this is definitely not recommended.

There are two commonly encountered circumstances where rewriting is
used, as illustrated by these examples:

   * The company whose domain is `hitch.fict.book' has a number of
     machines that exchange mail with each other behind a firewall, but
     only a single gateway to the outer world. The gateway rewrites
     `*.hitch.fict.book' as `hitch.fict.book'.

   * A machine rewrites the local parts of its own users so that, for
     example, "fp42@hitch.fict.book" becomes
     "Ford.Prefect@hitch.fict.book".

Configured address rewriting can take place at several different stages
of a message's processing. The main rewriting happens when a message is
received, but it can also happen when a new address is generated during
directing or routing (for example, by aliasing), and when a message is
transported.

The rewriting rules that appear in the rewriting section of the
configuration file (the sixth section) apply to addresses in incoming
messages, and to addresses that are generated from the envelope
recipients by aliasing or forwarding, unless "no_rewrite" is set on the
relevant directors. Basically, they apply to each address the first
time Exim sees it. These rules operate both on envelope addresses and
on addresses in header lines. Each rule specifies to which types of
address it applies.

At transport time, rewriting addresses in header lines can be specified
by setting the generic "headers_rewrite" option on a transport. This
option contains rules that are identical in form to those in the
rewrite section of the configuration file. In addition, the outgoing
envelope sender can be rewritten by means of the "return_path"
transport option, but it is not possible to rewrite envelope recipients
at transport time.

Rewriting of addresses in header lines applies only to those headers
that were received with the message, or, in the case of transport
rewriting, those that were added by a system filter. That is, it
applies only to those headers that are common to all copies of the
message. Header lines that are added by individual drivers (and which
are therefore specific to individual recipient addresses) are not
rewritten.

Unqualified addresses (those without a domain) in header lines are
qualified and then rewritten if they are in locally submitted messages,
or messages from hosts that are permitted to send unqualified envelope
addresses. Otherwise, unqualified addresses in header lines are neither
qualified nor rewritten.

The remainder of this chapter describes the rewriting rules that are
used in the rewriting section of the configuration file, and also in
the generic "headers_rewrite" option that can be set on any transport.



* Menu:

* Testing the rewriting rules that apply on input::
* Rewriting rules::
* Rewriting patterns::
* Rewriting replacements::
* Rewriting flags::
* Flags specifying which headers and envelope addresses to rewrite::
* The SMTP-time rewriting flag::
* Flags controlling the rewriting process::
* The additional relay checking flag::
* Rewriting examples::


File: exim.info,  Node: Testing the rewriting rules that apply on input,  Next: Rewriting rules,  Prev: Address rewriting,  Up: Address rewriting

Testing the rewriting rules that apply on input
===============================================

Exim's input rewriting configuration appears as the sixth part of the
run time configuration file. It can be tested by the -brw command line
option. This takes an address (which can be a full RFC 822 address) as
its argument. The output is a list of how the address would be
transformed by the rewriting rules for each of the different places it
might appear in an incoming message, that is, for each different header
and for the envelope sender and recipient fields.  For example,

     exim -brw ph10@exim.work.shop

might produce the output

       sender: Philip.Hazel@exim.work.shop
         from: Philip.Hazel@exim.work.shop
           to: ph10@exim.work.shop
           cc: ph10@exim.work.shop
          bcc: ph10@exim.work.shop
     reply-to: Philip.Hazel@exim.work.shop
     env-from: Philip.Hazel@exim.work.shop
       env-to: ph10@exim.work.shop

which shows that rewriting has been set up for that address when used
in any of the source fields, but not when it appears as a recipient
address.


File: exim.info,  Node: Rewriting rules,  Next: Rewriting patterns,  Prev: Testing the rewriting rules that apply on input,  Up: Address rewriting

Rewriting rules
===============

The rewriting section of the configuration file consists of lines of
rewriting rules in the form

     <source pattern>  <replacement>  <flags>

The flags are single characters which may appear in any order. Spaces
and tabs between them are ignored.

Rewriting rules that are specified for the "headers_rewrite" generic
transport option are given as a colon-separated list; each item in the
list takes the same format as a line in the main rewriting
configuration.

The formats of source patterns and replacement strings are described
below.  Each is terminated by white space. If a replacement string
contains spaces, which can happen for certain forms of expansion
expression, it must be enclosed in double quotes, and the normal
quoting conventions apply inside them.

For each address that could potentially be rewritten, the rules are
scanned in order, and replacements from earlier rules can themselves be
replaced as a result of later rules (but see the `q' and `R' flags).

The order in which header and envelope addresses are rewritten is
undefined, may change between releases, and must not be relied on, with
one exception: when a message is received, the envelope sender is always
rewritten first, before any header lines are rewritten. For example, the
replacement string for a rewrite of an address in "To:" must not assume
that the message's address in "From:" has (or has not) already been
rewritten.  However, a rewrite of "From:" may assume that the envelope
sender has already been rewritten.

$local_part and $domain can be used in the replacement string to refer
the address that is being rewritten. Note that complete lookup-driven
rewriting can be done by a rule of the form

     *@*   ${lookup ...

where the lookup key is derived from $1 and $2 or $local_part and
$domain.


File: exim.info,  Node: Rewriting patterns,  Next: Rewriting replacements,  Prev: Rewriting rules,  Up: Address rewriting

Rewriting patterns
==================

The source pattern can be in one of the following forms. It is not
enclosed in quotes, and there is no special processing of any
characters. It is not expanded. If it is a regular expression,
backslash characters should not be doubled.

   * An address containing a local part and a domain, either of which
     may start with an asterisk, implying independent wildcard
     matching, for example

          *@orchestra-land.fict.book

     If the domain is specified as a single @ character, it matches the
     primary host name. After matching, the numerical variables refer
     to the character strings matched by asterisks, with $1 associated
     with the first asterisk, while $0 refers to the entire address.
     For example, if the pattern

          *queen@*.fict.book

     is matched against the address "hearts-queen@wonderland.fict.book"
     then

          $0 = hearts-queen@wonderland.fict.book
          $1 = hearts-
          $2 = wonderland

     Note that if the local part does not start with an asterisk, but
     the domain does, it is $1 that contains the wild part of the
     domain.

   * A local part, possibly starting with an asterisk, and a lookup
     item (as in a domain list), for example

          root@lsearch;/special/domains

     If there is an asterisk in the local part, the value of the wild
     part is placed in the first numerical variable. If the lookup is a
     partial one, the wild part of the domain is placed in the next
     numerical variable, and the fixed part of the domain is placed in
     the succeeding variable. Supposed, for example, that the address
     "foo@bar.baz.com" is processed by a rewriting rule of the form

          *@partial-dbm;/some/dbm/file    <replacement string>

     and the key in the file that matches the domain is `*.baz.com'.
     Then

          $1 = foo
          $2 = bar
          $3 = baz.com

     If the address "foo@baz.com" is looked up, this matches the same
     wildcard file entry, and in this case $2 is set to the empty
     string, but $3 is still set to "baz.com". If a non-wild key is
     matched in a partial lookup, $2 is again set to the empty string
     and $3 is set to the whole domain.  For non-partial lookups, no
     numerical variables are set.

   * A local part, possibly starting with an asterisk, and a regular
     expression (as in a domain list), for example

          *.queen@^(wonderland|lookingglass)\.fict\.book$

     If there is an asterisk in the local part, the value of the wild
     part is placed in the first numerical variable. Any substrings
     captured by the regular expression are placed in numerical
     variables starting at $1 if there is no asterisk in the local
     part, or at $2 if there is.

   * A lookup without a local part, for example

          partial-dbm;/rewrite/database

     This works as for an "address list" configuration item - the
     domain is first looked up, possibly partially, and if that fails,
     the whole address is then looked up (not partially). When a
     partial lookup succeeds, the numerical variable $1 contains the
     wild part of the domain, and $2 contains the fixed part. The `@@'
     form of address list lookup can also be used.

   * A single regular expression. This is matched against the entire
     subject address, with the domain part lower-cased. After matching,
     the numerical variables refer to the bracketed `capturing'
     sub-expressions, with $0 referring to the entire address. For
     example, if the pattern

          ^(red|white)\.king@(wonderland|lookingglass)\.fict\.book$

     is matched against the address "red.king@lookingglass.fict.book"
     then

          $0 = "red.king@lookingglass.fict.book"
          $1 = "red"
          $2 = "lookingglass"

     Note that because the pattern part of a rewriting rule is
     terminated by white space, no white space may be present in the
     regular expression.


File: exim.info,  Node: Rewriting replacements,  Next: Rewriting flags,  Prev: Rewriting patterns,  Up: Address rewriting

Rewriting replacements
======================

If the replacement string for a rule is a single asterisk, addresses
that match the pattern and flags are not rewritten, and no subsequent
rewriting rules are scanned. For example,

     hatta@lookingglass.fict.book  *  f

specifies that "hatta@lookingglass.fict.book" is never to be rewritten
in "From:" headers.

Otherwise, the replacement string is expanded and must yield a fully
qualified address. Within the expansion, the variables $local_part and
$domain refer to the address that is being rewritten. Any letters they
contain retain their original case - they are not lower cased. The
numerical variables are set up according to the type of pattern that
matched the address, as described above. If the expansion is forced to
fail by the presence of `fail' in a conditional or lookup item,
rewriting by the current rule is abandoned. Any other expansion failure
causes the entire rewriting operation to be abandoned, and an entry
written to the panic log.


File: exim.info,  Node: Rewriting flags,  Next: Flags specifying which headers and envelope addresses to rewrite,  Prev: Rewriting replacements,  Up: Address rewriting

Rewriting flags
===============

There are four different kinds of flag that may appear on rewriting
rules:

   * Flags that specify which headers and envelope addresses to
     rewrite: E, F, T, b, c, f, h, r, s, t.

   * A flag that specifies rewriting at SMTP time: S.

   * Flags that control the rewriting process: Q, q, R, w.

   * A special-purpose flag for additional relay checking: X.

For rules that are part of the "headers_rewrite" generic transport
option, E, F, T, S, and X are not permitted.


File: exim.info,  Node: Flags specifying which headers and envelope addresses to rewrite,  Next: The SMTP-time rewriting flag,  Prev: Rewriting flags,  Up: Address rewriting

Flags specifying which headers and envelope addresses to rewrite
================================================================

If none of the following flag letters, nor the `S' flag (see section
"The SMTP-time rewriting flag") are present, a main rewriting rule
applies to all headers and to both the sender and recipient fields of
the envelope, whereas a transport-time rewriting rule just applies to
all headers.  Otherwise, the rewriting rule is skipped unless the
relevant addresses are being processed.

     E       rewrite all envelope fields
     F       rewrite the envelope From field
     T       rewrite the envelope To field
     b       rewrite the "Bcc:" header
     c       rewrite the "Cc:" header
     f       rewrite the "From:" header
     h       rewrite all headers
     r       rewrite the "Reply-To:" header
     s       rewrite the "Sender:" header
     t       rewrite the "To:" header

You should be particularly careful about rewriting "Sender:" headers,
and restrict this to special known cases in your own domains.


File: exim.info,  Node: The SMTP-time rewriting flag,  Next: Flags controlling the rewriting process,  Prev: Flags specifying which headers and envelope addresses to rewrite,  Up: Address rewriting

The SMTP-time rewriting flag
============================

The rewrite flag `S' specifies a rewrite of incoming envelope addresses
at SMTP time, as soon as an address is received in a MAIL or RCPT
command, and before any other processing; even before syntax checking.
The pattern is required to be a regular expression, and it is matched
against the whole of the data for the command, including any
surrounding angle brackets.  This form of rewrite rule allows for the
handling of addresses that are not compliant with RFCs 821 and 822 (for
example, `bang paths' in batched SMTP input). Because the input is not
required to be a syntactically valid address, the variables $local_part
and $domain are not available during the expansion of the replacement
string. The result of rewriting replaces the original address in the
MAIL or RCPT command.


File: exim.info,  Node: Flags controlling the rewriting process,  Next: The additional relay checking flag,  Prev: The SMTP-time rewriting flag,  Up: Address rewriting

Flags controlling the rewriting process
=======================================

There are four flags which control the way the rewriting process works.
These take effect only when a rule is invoked, that is, when the
address is of the correct type (matches the flags) and matches the
pattern.

   * If the `Q' flag is set on a rule, the rewritten address is
     permitted to be an unqualified local part. It is qualified with
     "qualify_recipient". In the absence of `Q' the rewritten address
     must always include a domain.

   * If the `q' flag is set on a rule, no further rewriting rules are
     considered, even if no rewriting actually takes place because of a
     `fail' in the expansion. The `q' flag is not effective if the
     address is of the wrong type (does not match the flags) or does
     not match the pattern.

   * The `R' flag causes a successful rewriting rule to be re-applied to
     the new address, up to ten times. It can be combined with the `q'
     flag, to stop rewriting once it fails to match (after at least one
     successful rewrite).

   * When an address in a header is rewritten, the rewriting normally
     applies only to the working part of the address, with any comments
     and RFC 822 `phrase' left unchanged. For example, rewriting might
     change

          From: Ford Prefect <fp42@restaurant.hitch.fict.book>

     into

          From: Ford Prefect <prefectf@hitch.fict.book>

     Sometimes there is a need to replace the whole address item, and
     this can be done by adding the flag letter `w' to a rule. If this
     is set on a rule that causes an address in a header to be
     rewritten, the entire address is replaced, not just the working
     part. The replacement must be a complete RFC 822 address,
     including the angle brackets if necessary. When the `w' flag is
     set on a rule that causes an envelope address to be rewritten, all
     but the working part of the replacement address is discarded.


File: exim.info,  Node: The additional relay checking flag,  Next: Rewriting examples,  Prev: Flags controlling the rewriting process,  Up: Address rewriting

The additional relay checking flag
==================================

The `X' flag is a slightly strange oddity that adds additional checking
to "sender_address_relay". Whenever an address passes the
"sender_address_relay" check, if there are any rewriting rules with the
`X' flag set, the address is rewritten and if this makes any change to
the address, it must verify successfully for the relaying to be
permitted.

We use this in Cambridge as follows: users have a centrally registered
address in the virtual domain "cam.ac.uk", but there are a number of
different hosts where they actually have their accounts and from which
they can read mail using IMAP or POP. It is desirable to prevent them
using hosts other than those on which they have accounts as outgoing
relays, and yet to permit the sending addresses to contain the
"cam.ac.uk" domain. Since the user names are the same on the relay
hosts as in the "cam.ac.uk" domain, a rewriting rule of the form

     *@cam.ac.uk  $1@${qualify_domain}  X

means that any sender address of the form "user@cam.ac.uk" is
acceptable only if "user" has an account on the local host. This also
has the virtue of detecting typos in the configurations of users' MUAs.


File: exim.info,  Node: Rewriting examples,  Prev: The additional relay checking flag,  Up: Address rewriting

Rewriting examples
==================

Here is an example of the two common rewriting paradigms:

     *@*.hitch.book.fict  $1@hitch.book.fict
     *@hitch.book.fict    ${lookup{$1}dbm{/etc/realnames}\
                          {$value}fail}@hitch.book.fict bctfrF

Note the use of `fail' in the lookup expansion. This causes the string
expansion to fail, and in this context it has the effect of leaving the
original address unchanged, but Exim goes on to consider subsequent
rewriting rules, if any, since the `q' flag is not present in that
rule. An alternative to `fail' would be to supply $1 explicitly, which
would cause the rewritten address to be the same as before, at the cost
of a small bit of processing. Not supplying either of these is an
error, since the rewritten address would then contain no local part.

The first example above replaces the domain with a superior, more
general domain. This may not be desirable for certain local parts. If
the rule

     root@*.hitch.book.fict  *

were inserted as the first rule, rewriting would be suppressed for the
local part "root" at any domain ending in "hitch.book.fict".

Rewriting can be made conditional on a number of tests, by making use of
${if in the expansion item. For example, to apply a rewriting rule only
to messages that originate outside the local host:

     *@*.hitch.book.fict  "${if !eq {$sender_host_address}{}\
                           {$1@hitch.book.fict}fail}"

The replacement string is quoted in this example because it contains
white space.

Exim does not handle addresses in the form of `bang paths'. If it sees
such an address it treats it as an unqualified local part which it
qualifies with the local qualification domain (if the source of the
message is local or if the remote host is permitted to send unqualified
addresses). Rewriting can sometimes be used to handle simple bang paths
with a fixed number of components. For example, the rule

     ^([^!]+)!(.*)@your\.domain$   $2@$1

rewrites a two-component bang path `host.name!user' as the domain
address `user@host.name'. However, there is a security implication in
doing this as a normal rewriting rule for envelope addresses. It can
provide a backdoor method for using your system as a relay, since the
incoming addresses appear to be local. If the bang path addresses are
received via SMTP, it is safer to use the `S' flag to rewrite them as
they are received, so that relay checking can be done on the rewritten
addresses.


File: exim.info,  Node: SMTP authentication,  Next: The plaintext authenticator,  Prev: Address rewriting,  Up: Top

SMTP authentication
*******************

The seventh part of Exim's run time configuration, following the
rewriting configuration, is concerned with SMTP authentication. This is
an extension to the SMTP protocol, described in RFC 2554, which allows
a client SMTP host to authenticate itself to a server. By this means a
server might, for example, recognize clients that are permitted to use
it as a relay. SMTP authentication is not of relevance to the transfer
of mail between servers that have no managerial connection with each
other.

Very briefly, the way SMTP authentication works is as follows:

   * The server advertises a number of authentication "mechanisms".

   * The client issues an AUTH command, naming a specific mechanism.
     The command may, optionally, contain some authentication data.

   * The server may issue one or more "challenges", to which the client
     must send appropriate responses. In the simple authentication
     mechanisms, the challenges are just prompts for user names and
     passwords. The server does not have to issue any challenges - in
     some mechanisms the relevant data may all be transmitted with the
     AUTH command.

   * The server either accepts or denies authentication.

   * If authentication succeeds, the client may optionally make use of
     the AUTH option on the MAIL command to pass an authenticated
     sender in subsequent mail transactions. Authentication lasts for
     the remainder of the SMTP connection.

   * If authentication fails, the client may give up, or it may try a
     different authentication mechanism, or it may try transfering mail
     over the unauthenticated connection.

If you are setting up a client, and want to know which authentication
mechanisms the server supports, you can use Telnet to connect to port
25 (the SMTP port) on the server, and issue an EHLO command. The
response to this includes the list of supported mechanisms.

When Exim is receiving SMTP mail, it is acting as a server; when it is
sending out messages over SMTP, it is acting as a client. Configuration
options are provided for use in both these circumstances. The different
authentication mechanisms. These are configured by specifying
"authenticator" drivers for Exim. Like the directors, routers, and
transports, which authenticators are included in the binary is
controlled by build-time definitions. Two are currently available,
included by setting

     AUTH_CRAM_MD5=yes
     AUTH_PLAINTEXT=yes

in `Local/Makefile', respectively. The first of these supports the
CRAM-MD5 authentication mechanism (RFC 2195), while the second can be
configured to support the PLAIN authentication mechanism (RFC 2595) or
the LOGIN mechanism, which is not formally documented, but used by
several MUAs.

Almost all the code for handling authentication is omitted from Exim
unless at least one AUTH_xxx is defined. This includes the code for
implementing configuration options such as "auth_hosts". Attempts to
use such options provoke `unknown option' errors when no authentication
code is included in the binary.

The authenticators are configured using the same syntax as other
drivers (see chapter "Driver specifications"). If none are required,
the entire seventh section of the configuration file may be omitted. If
at least one authenticator is included in the binary, the contents of
the configuration can be obtained by running one of

     exim -bP authenticator_list
     exim -bP authenticators
     exim -bP authenticator <authenticator name>

Each authenticator can have both server and client functions. To make
it clear which options apply to which, the prefixes "server_" and
"client_" are used on option names which are specific to either the
server or the client function, respectively. Server and client
functions are disabled if none of their options are set. If an
authenticator is to be used for both server and client functions, a
single definition, using both sets of options, is required.  For
example:

     cram:
       driver = cram_md5
       public_name = CRAM-MD5
       server_secret = ${if eq{$1}{ph10}{secret1}fail}
       client_name = ph10
       client_secret = secret2

The "server_" option is used when Exim is acting as a server, and the
"client_" options when it is acting as a client.

Descriptions of the individual authenticators are given in subsequent
chapters.  The remainder of this chapter covers the generic options for
the authenticators, followed by general discussion of the way
authentication works.



* Menu:

* Generic options for authenticators::
* Authentication on an Exim server::
* Testing server authentication::
* Authenticated senders::
* Authentication by an Exim client::


File: exim.info,  Node: Generic options for authenticators,  Next: Authentication on an Exim server,  Prev: SMTP authentication,  Up: SMTP authentication

Generic options for authenticators
==================================



* Menu:

* driver::
* public_name::
* server_set_id::
* server_mail_auth_condition::


File: exim.info,  Node: driver,  Next: public_name,  Prev: Generic options for authenticators,  Up: Generic options for authenticators

driver _option_
---------------

Type: string
Default: unset

This option must always be set. It specifies which of the available
authenticators is to be used.


File: exim.info,  Node: public_name,  Next: server_set_id,  Prev: driver,  Up: Generic options for authenticators

public_name _option_
--------------------

Type: string
Default: unset

This option specifies the name of the authentication mechanism which
the driver implements, and by which it is known to the outside world.
These names should contain only upper case letters, digits,
underscores, and hyphens (RFC 2222), but Exim in fact matches them
caselessly. If "public_name" is not set, it defaults to the driver
instance's name.

The public names of authenticators that are configured as servers are
advertised by Exim when it receives an EHLO command, in the order in
which they are defined. When an AUTH command is received, the list of
authenticators is scanned in definition order for one whose public name
matches the mechanism given in the AUTH command.


File: exim.info,  Node: server_set_id,  Next: server_mail_auth_condition,  Prev: public_name,  Up: Generic options for authenticators

server_set_id _option_
----------------------

Type: string, expanded
Default: unset

When an Exim server successfully authenticates a client, this string is
expanded using data from the authentication, and preserved for any
incoming messages in the variable $authenticated_id. It is also
included in the log lines for incoming messages. For example, a
user/password authenticator configuration might preserve the user name
which was used to authenticate, and refer to it subsequently during
delivery of the message.


File: exim.info,  Node: server_mail_auth_condition,  Prev: server_set_id,  Up: Generic options for authenticators

server_mail_auth_condition _option_
-----------------------------------

Type: string, expanded
Default: unset

This option allows a server to discard authenticated sender addresses
supplied in MAIL commands according to configured conditions. If the
option is unset, addresses supplied by the AUTH option of MAIL commands
are always accepted. Otherwise, when an authenticated client supplies
an AUTH value on a MAIL command, the value of this option is expanded.
If it yields an empty string, `0', `no', or `false', the AUTH address
is ignored. If the expansion yields any other value, the AUTH address
is retained and passed on with the message. During the expansion, the
address that was supplied by the AUTH keyword is available in
$authenticated_sender.


File: exim.info,  Node: Authentication on an Exim server,  Next: Testing server authentication,  Prev: Generic options for authenticators,  Up: SMTP authentication

Authentication on an Exim server
================================

When any server authentication mechanisms are configured, the SMTP AUTH
command is accepted from any connected client host. If, however, the
client host matches an item in "auth_hosts", it is required to
authenticate itself before any commands other than HELO, EHLO, HELP,
AUTH, NOOP, RSET, or QUIT are accepted.

You can insist that any client that uses the AUTH command for
authentication must start a TLS encrypted session first, by setting
"auth_over_tls_hosts". For example,

     auth_over_tls_hosts = *

means that all authentication must take place over secure sessions. See
chapter "Encrypted SMTP connections using TLS/SSL" for details of TLS
encryption.

A client that matches an item in "host_auth_accept_relay" is permitted
to relay to any domain, provided that it is authenticated, whether or
not it matches "auth_hosts". In other words, an authenticated client is
permitted to relay if it matches either "host_accept_relay" or
"host_auth_accept_relay", whereas an unauthenticated client host may
relay only if it matches "host_accept_relay".

Normally, an Exim server advertises the authentication mechanisms it
supports in response to any EHLO command. However, if
"auth_always_advertise" is set false, Exim advertises availability of
the AUTH command only if the calling host is in "auth_hosts", or if it
is in "host_auth_accept_relay" and not in "host_accept_relay". In other
words, it advertises only when the host is required always to
authenticate or to authenticate in order to relay.

Otherwise, Exim does not advertise AUTH, though it is always prepared to
accept it. Certain mail clients (for example, Netscape) require the
user to provide a name and password for authentication if AUTH is
advertised, even though it may not be needed (the host may be in
"host_accept_relay").  Unsetting "auth_always_advertise" makes these
clients more friendly in these circumstances, while still allowing you
to use combinations such as

     host_auth_accept_relay = *
     host_accept_relay = 10.9.8.0/24

without needing to fill up "host_auth_accept_relay" with exceptions.

When a message is received from an authenticated host, the value of
$received_protocol is set to `asmtp' instead of `esmtp', and
$sender_host_authenticated contains the name (not the public name) of
the authenticator driver which successfully authenticated the client
from which the message was received. It is empty if there was no
successful authentication.


File: exim.info,  Node: Testing server authentication,  Next: Authenticated senders,  Prev: Authentication on an Exim server,  Up: SMTP authentication

Testing server authentication
=============================

Exim's -bh option can be useful for testing server authentication
configurations. The data for the AUTH command has to be sent encoded in
base 64. A quick way to produce such data for testing is the following
Perl script:

     use MIME::Base64;
     printf ("%s", encode_base64(eval "\"$ARGV[0]\""));

This interprets its argument as a Perl string, and then encodes it. The
interpretation as a Perl string allows binary zeros, which are required
for some kinds of authentication, to be included in the data. For
example, a command line to run this script on such data might be

     encode '\0user\0password'

Note the use of single quotes to prevent the shell interpreting the
backslashes, so that they can be interpreted by Perl to specify
characters whose code value is zero. If you have the "mimencode"
command installed, another way to do this is to run the command

     echo -n `\0user\0password' | mimencode

(but some versions of "echo" do not recognize the -n option).

Warning: If either of the strings starts with an octal digit, you must
use three zeros instead of one after the leading backslash. If you do
not, the octal digit that starts your string will be incorrectly
interpreted as part of the code for the first character.


File: exim.info,  Node: Authenticated senders,  Next: Authentication by an Exim client,  Prev: Testing server authentication,  Up: SMTP authentication

Authenticated senders
=====================

When a client host has authenticated itself, Exim pays attention to the
AUTH parameter on incoming SMTP MAIL commands. Otherwise, it accepts
the syntax, but ignores the data. Unless the data is the string `<>',
it is set as the authenticated sender of the message. The value is
available during delivery in the $authenticated_sender variable, and is
passed on to other hosts to which Exim authenticates as a client. Do
not confuse this value with $authenticated_id, which is a string
obtained from the authentication process, and which is not usually a
complete email address.


File: exim.info,  Node: Authentication by an Exim client,  Prev: Authenticated senders,  Up: SMTP authentication

Authentication by an Exim client
================================

The "smtp" transport has an option called "authenticate_hosts" if Exim
is built with authentication support. When the "smtp" transport
connects to a server that announces support for authentication, and
also matches an entry in "authenticate_hosts", Exim (as a client) tries
to authenticate as follows:

   * For each authenticator that is configured as a client, it searches
     the authentication mechanisms announced by the server for one
     whose name matches the public name of the authenticator.

   * When it finds one that matches, it runs the authenticator's client
     code.  The variables $host and $host_address are available for any
     string expansions that the client might do. They are set to the
     server's name and IP address. If any expansion is forced to fail,
     the authentication attempt is abandoned. Otherwise an expansion
     failure causes delivery to be deferred.

   * If the result is a temporary error or a timeout, Exim abandons
     trying to send the message to the host for the moment. It will try
     again later. If there are any backup hosts available, they are
     tried in the usual way.

   * If the response to authentication is a permanent error (5xx code),
     Exim carries on searching the list of authenticators. If all
     authentication attempts give permanent errors, or if there are no
     attempts because no mechanisms match, it tries to deliver the
     message unauthenticated.

When Exim has authenticated itself to a remote server, it adds the AUTH
parameter to the MAIL commands it sends, if it has got an authenticated
sender for the message. If a local process calls Exim to send a
message, the sender address that is built from the login name and
"qualify_domain" is treated as authenticated.


File: exim.info,  Node: The plaintext authenticator,  Next: The cram_md5 authenticator,  Prev: SMTP authentication,  Up: Top

The plaintext authenticator
***************************

The "plaintext" authenticator can be configured to support the PLAIN
and LOGIN authentication mechanisms, both of which transfer
authentication data as plain (unencrypted) text, though encoded in base
64.  The use of plain text is a security risk. If you use one of these
mechanisms without also making use of SMTP encryption (see chapter
"Encrypted SMTP connections using TLS/SSL") you should not use the same
passwords for SMTP connections as you do for login accounts.



* Menu:

* Using plaintext in a server::
* Using plaintext in a server (continued)::
* Using plaintext in a client::
* Using plaintext in a client (continued)::


File: exim.info,  Node: Using plaintext in a server,  Next: Using plaintext in a server (continued),  Prev: The plaintext authenticator,  Up: The plaintext authenticator

Using plaintext in a server
===========================

When running as a server, "plaintext" performs the authentication test
by expanding a string. It has the following options:



* Menu:

* server_prompts (plaintext)::
* server_condition (plaintext)::


File: exim.info,  Node: server_prompts (plaintext),  Next: server_condition (plaintext),  Prev: Using plaintext in a server,  Up: Using plaintext in a server

server_prompts (plaintext) _option_
-----------------------------------

Type: string, expanded
Default: unset

This option contains a colon-separated list of prompt strings.


File: exim.info,  Node: server_condition (plaintext),  Prev: server_prompts (plaintext),  Up: Using plaintext in a server

server_condition (plaintext) _option_
-------------------------------------

Type: string, expanded
Default: unset

This option must be set in order to configure the driver as a server.
Its use is described below.


File: exim.info,  Node: Using plaintext in a server (continued),  Next: Using plaintext in a client,  Prev: Using plaintext in a server,  Up: The plaintext authenticator

The data sent with the AUTH command or in response to subsequent
prompts is encoded in base 64, and so may contain any byte values when
decoded. If any data was supplied with the command, it is treated as a
list of NUL-separated strings which are placed in the expansion
variables $1, $2, etc. If there are more strings in "server_prompts"
than the number of strings supplied with the AUTH command, the
remaining prompts are used to obtain more data. Each response from the
client may be a list of NUL-separated strings.

Once a sufficient number of data strings has been received,
"server_condition" is expanded. Failure of the expansion (forced or
otherwise) causes a temporary error code to be returned. If the result
of a successful expansion is an empty string, `0', `no', or `false',
authentication fails. If the result of the expansion is `1', `yes', or
`true', authentication succeeds and the generic "server_set_id" option
is expanded and saved in $authenticated_id. For any other result, a
temporary error code is returned, with the expanded string as the error
text.

The PLAIN authentication mechanism (RFC 2595) specifies that three
strings be sent with the AUTH command. The second and third of them are
a user/password pair. Using a single fixed user and password as an
example, this could be configured as follows:

     fixed_plain:
       driver = plaintext
       public_name = PLAIN
       server_condition = \
         ${if and {{eq{$2}{ph10}}{eq{$3}{secret}}}{yes}{no}}
       server_set_id = $2

This would be advertised in the response to EHLO as

     250-AUTH PLAIN

and a client host could authenticate itself by sending the command

     AUTH PLAIN AHBoMTAAc2VjcmV0

The argument string is encoded in base 64, as required by the RFC. This
example, when decoded, is `<NUL>ph10<NUL>secret', where <NUL> represents
a zero byte. This is split up into three strings, the first of which is
empty.  The condition checks that the second two are `ph10' and
`secret' respectively.  Because no prompt strings are set, if no data
is given with the AUTH command, authentication fails.

A more sophisticated instance of this authenticator could make use of
the user name in $2 to look up a password in a file or database, and
maybe do an encrypted comparison (see "crypteq" in chapter "String
expansions"). Note, however, that the authentication data has traversed
the network in clear, albeit encoded as a base 64 string.

The LOGIN authentication mechanism is not documented in any RFC, but is
in use in a number of programs. No data is sent with the AUTH command.
Instead, a user name and password are supplied separately, in response
to prompts. The plaintext authenticator can be configured to support
this as in this example:

     fixed_login:
       driver = plaintext
       public_name = LOGIN
       server_prompts = User Name : Password
       server_condition = \
         ${if and {{eq{$1}{ph10}}{eq{$2}{secret}}}{yes}{no}}
       server_set_id = $1

Some clients are very particular about the precise text of the prompts.
For example, Outlook Express is reported to recognize only `Username:'
and `Password:'.

This authenticator would accept data with the AUTH command (in
contravention of the specification of LOGIN), but if the client does
not supply it (as is the case for LOGIN clients), the prompt strings
are used to obtain two data items.


File: exim.info,  Node: Using plaintext in a client,  Next: Using plaintext in a client (continued),  Prev: Using plaintext in a server (continued),  Up: The plaintext authenticator

Using plaintext in a client
===========================

The "plaintext" authenticator has just one client option:



* Menu:

* client_send (plaintext)::


File: exim.info,  Node: client_send (plaintext),  Prev: Using plaintext in a client,  Up: Using plaintext in a client

client_send (plaintext) _option_
--------------------------------

Type: string, expanded
Default: unset

The string is a colon-separated list of authentication data strings.
Each string is independently expanded before being sent to the server.
The first string is sent with the AUTH command; any more strings are
sent in response to prompts from the server.

Because the PLAIN authentication mechanism requires NUL (zero) bytes in
the data sent with the AUTH command, further processing is applied to
each string before it is sent. If there are any single circumflex
characters in the string, they are converted to NULs. Should an actual
circumflex be required as data, it must be doubled in the string.


File: exim.info,  Node: Using plaintext in a client (continued),  Prev: Using plaintext in a client,  Up: The plaintext authenticator

This is an example of a client configuration that implements the PLAIN
authentication mechanism with a fixed name and password:

     fixed_plain:
       driver = plaintext
       public_name = PLAIN
       client_send = ^ph10^secret

The lack of colons means that the entire text is sent with the AUTH
comand, with the circumflex characters converted to NULs. A similar
example that uses the LOGIN mechanism is:

     fixed_login:
       driver = plaintext
       public_name = LOGIN
       client_send = : ph10 : secret

The initial colon ensures that no data is sent with the AUTH command
itself. The remaining strings are sent in response to prompts.


File: exim.info,  Node: The cram_md5 authenticator,  Next: Encrypted SMTP connections using TLS/SSL,  Prev: The plaintext authenticator,  Up: Top

The cram_md5 authenticator
**************************

The CRAM-MD5 authentication mechanism is described in RFC 2195. The
server sends a `challenge' string to the client, and the response
consists of a `user name' and the CRAM-MD5 digest of the challenge
string combined with a secret string (password) which is known to both
server and client. Thus the secret does not get sent over the network
as plain text, which makes this authenticator more secure than
"plaintext".



* Menu:

* Using cram_md5 as a server::
* Using cram_md5 as a server (continued)::
* Using cram_md5 as a client::
* Using cram_md5 as a client (continued)::


File: exim.info,  Node: Using cram_md5 as a server,  Next: Using cram_md5 as a server (continued),  Prev: The cram_md5 authenticator,  Up: The cram_md5 authenticator

Using cram_md5 as a server
==========================

This authenticator has one server option, which must be set to
configure the authenticator as a server.



* Menu:

* server_secret (cram_md5)::


File: exim.info,  Node: server_secret (cram_md5),  Prev: Using cram_md5 as a server,  Up: Using cram_md5 as a server

server_secret (cram_md5) _option_
---------------------------------

Type: string, expanded
Default: unset

When the server receives the client's response, the `user name' is
placed in the expansion variable $1, and "server_secret" is expanded to
obtain the password for that user. The server then computes the
CRAM-MD5 digest that the client should have sent, and checks that it
received the correct string. If the expansion of "server_secret" is
forced to fail, authentication fails. If the expansion fails for some
other reason, a temporary error code is returned to the client.


File: exim.info,  Node: Using cram_md5 as a server (continued),  Next: Using cram_md5 as a client,  Prev: Using cram_md5 as a server,  Up: The cram_md5 authenticator

For example, the following authenticator checks that the user name
given by the client is `ph10', and if so, uses `secret' as the
password. For any other user name, authentication fails. A more
sophisticated version might look up the secret string in a file, using
the user name as the key.

     fixed_cram:
       driver = cram_md5
       public_name = CRAM-MD5
       server_secret = ${if eq{$1}{ph10}{secret}fail}
       server_set_id = $1

If authentication succeeds, the setting of "server_set_id" preserves
the user name in $authenticated_id.


File: exim.info,  Node: Using cram_md5 as a client,  Next: Using cram_md5 as a client (continued),  Prev: Using cram_md5 as a server (continued),  Up: The cram_md5 authenticator

Using cram_md5 as a client
==========================

When used as a client, the "cram_md5" authenticator has two options:



* Menu:

* client_name (cram_md5)::
* client_secret (cram_md5)::


File: exim.info,  Node: client_name (cram_md5),  Next: client_secret (cram_md5),  Prev: Using cram_md5 as a client,  Up: Using cram_md5 as a client

client_name (cram_md5) _option_
-------------------------------

Type: string, expanded
Default: the primary host name

This string is expanded, and the result used as the `user name' data
when computing the response to the server's challenge.


File: exim.info,  Node: client_secret (cram_md5),  Prev: client_name (cram_md5),  Up: Using cram_md5 as a client

client_secret (cram_md5) _option_
---------------------------------

Type: string, expanded
Default: unset

This option must be set for the authenticator to work as a client. Its
value is expanded and the result used as the secret string when
computing the response.


File: exim.info,  Node: Using cram_md5 as a client (continued),  Prev: Using cram_md5 as a client,  Up: The cram_md5 authenticator

Different user names and secrets can be used for different servers by
referring to $host or $host_address in the options.

Forced failure of either expansion string is treated as an indication
that this authenticator is not prepared to handle this case. Exim moves
on to the next configured client authenticator. Any other expansion
failure causes Exim to give up trying to send the message to the
current server.

A simple example configuration of a "cram_md5" authenticator, using
fixed strings, is:

     fixed_cram:
       driver = cram_md5
       public_name = CRAM-MD5
       client_name = ph10
       client_secret = secret


File: exim.info,  Node: Encrypted SMTP connections using TLS/SSL,  Next: Customizing error and warning messages,  Prev: The cram_md5 authenticator,  Up: Top

Encrypted SMTP connections using TLS/SSL
****************************************

Support for TLS (Transport Layer Security), otherwise known as SSL
(Secure Sockets Layer), is implemented by making use of the OpenSSL
library. There is no cryptographic code in the Exim distribution
itself. In order to use this feature you must install OpenSSL, and then
build a version of Exim that includes TLS support. You also need to
understand the basic concepts of encryption at a managerial level, and
in particular, the way that public keys, private keys, and certificates
are used.

RFC 2487 defines how SMTP connections can make use of encryption. Once a
connection is established, the client issues a STARTTLS command. If the
server accepts this, they negotiate an encryption mechanism. If the
negotiation succeeds, the data that subsequently passes between them is
encrypted.



* Menu:

* Configuring Exim to use TLS as a server::
* Configuring Exim to use TLS as a client::
* Multiple messages on the same TCP/IP connection::
* Certificates and all that::


File: exim.info,  Node: Configuring Exim to use TLS as a server,  Next: Configuring Exim to use TLS as a client,  Prev: Encrypted SMTP connections using TLS/SSL,  Up: Encrypted SMTP connections using TLS/SSL

Configuring Exim to use TLS as a server
=======================================

When Exim has been built with TLS support, it advertises the
availability of the STARTTLS command to client hosts that match
"tls_advertise_hosts", but not to any others. The default value of this
option is unset, which means that STARTTLS is not advertised at all.
This default is chosen because it is sensible for systems that want to
use TLS only as a client. To make it work as a server, you must set
"tls_advertise_hosts" to match some hosts. You can, of course, set it
to * to match all hosts. However, this is not all you need to do. TLS
sessions to a server won't work without some further configuration at
the server end (see below).

If a client issues a STARTTLS command and there is some configuration
problem in the server code, the command is rejected with a 454 error.
If the client persists in trying to issue SMTP commands, all except
QUIT are rejected with the error

     554 Security failure

If a STARTTLS command is issued within an existing TLS session, it is
rejected with a 554 error code.

It is rumoured that all existing clients that support TLS/SSL use RSA
encryption. To make this work you need to set, in the server,

     tls_certificate = /some/file/name
     tls_privatekey = /some/file/name

The first file contains the server's X509 certificate, and the second
contains the private key that goes with it. These files need to be
readable by the Exim user. They can be the same file if both the
certificate and the key are contained within it. If you don't
understand about certificates and keys, please try to find a source of
this background information, which is not Exim-specific. (There are a
few comments below.)

With just these two options set, Exim will work as a server with
clients such as Netscape. It does not require the client to have a
certificate (but see below for how to insist on this). There is one
other option that may be needed in other situations. If

     tls_dhparam = /some/file/name

is set, the SSL library is initialized for the use of Diffie-Hellman
ciphers with the parameters contained in the file. This increases the
set of ciphers that the server supports. (See the command

     openssl dhparam

for a way of generating this data.)

The strings supplied for these options are expanded every time a client
host connects. It is therefore possible to use different certificates
and keys for different hosts, if you so wish, by making use of the
client's IP address in $sender_host_address to control the expansion.
If a string expansion is forced to fail, Exim behaves as if the option
is not set.

The variable $tls_cipher is set to the cipher that was negotiated for an
incoming TLS connection. It is included in the "Received:" header of an
incoming message (by default - you can, of course, change this), and it
is also included in the log line that records a message's arrival,
keyed by `X=', unless "tls_log_cipher" is set false.

If you want to enforce conditions on incoming TLS connections, you must
set "tls_verify_hosts" to match the relevant clients. By default this
host list is unset. You could, of course, use

     tls_verify_hosts = *

to make it apply to all TLS connections. When a client host is in this
list, two further options are relevant:

   * "tls_verify_ciphers" contains a colon-separated list of permitted
     ciphers. The list is passed to the OpenSSL library, so it must
     always be colon-separated - Exim's alternate separator feature
     does not apply. For example:

          tls_verify_ciphers = DES-CBC3-SHA:IDEA-CBC-MD5

     With this option set, all TLS sessions must use one of the listed
     ciphers.

   * "tls_verify_certificates" contains the name of a file or a
     directory that contains a collection of expected certificates. A
     file can contain multiple certificates, concatenated end to end.
     If a directory is used, each certificate must be in a separate
     file, with a name (or a symbolic link) of the form <hash>.0, where
     <hash> is a hash value constructed from the certificate. You can
     compute the relevant hash by running the command

          openssl x509 -hash -noout -in /cert/file

     where "/cert/file" contains a single certificate.

     When "tls_verify_certificates" is set, Exim always requests a
     certificate from the client, and fails if one is not provided. The
     value of the Distinguished Name of the certificate is made
     available in the variable $tls_peerdn during subsequent processing
     of the message.  Because it is often a long text string, it is not
     included in the log line or "Received:" header by default. You can
     arrange for it to be logged, keyed by `DN=', by setting
     "tls_log_peerdn", and you can use "received_header_text" to change
     the "Received:" header.

Both these options are expanded before use, so again you can make them
do different things for different hosts.

You can insist that certain client hosts use TLS, by setting
"tls_hosts" to match them. When a host is in "tls_hosts", STARTTLS is
always advertised to it, even if it is not in "tls_advertise_hosts". If
such a host attempts to send a message without starting a TLS session,
the MAIL command is rejected with the error

     503 Use of TLS required

You can permit client hosts to relay, provided they are in a TLS
session, by setting "tls_host_accept_relay". Note that all the host
relay checks are alternatives. Relaying is permitted if any of the
checks is passed, that is, if

   * The host matches "host_accept_relay", OR

   * The host is authenticated and matches "host_auth_accept_relay" OR

   * The host is using a TLS session and matches
     "tls_host_accept_relay".

Using "tls_host_accept_relay" probably makes sense only if you are
checking the  client's certificate.

You can insist that any client that uses the AUTH command for
authentication must start a TLS session first, by setting
"auth_over_tls_hosts". For example,

     auth_over_tls_hosts = *

means that all authentication must take place over secure sessions. This
setting does not force the matching hosts to use AUTH, but if they do,
they must issue STARTTLS first. The availability of the AUTH command is
advertised to such hosts only after a TLS session has been started.


File: exim.info,  Node: Configuring Exim to use TLS as a client,  Next: Multiple messages on the same TCP/IP connection,  Prev: Configuring Exim to use TLS as a server,  Up: Encrypted SMTP connections using TLS/SSL

Configuring Exim to use TLS as a client
=======================================

The "tls_log_cipher" and "tls_log_peerdn" options apply to outgoing SMTP
deliveries as well as to incoming, the latter one causing logging of the
server certificate's DN. The remaining client configuration for TLS is
all within the "smtp" transport.

It is not necessary to set any options to have TLS work in the "smtp"
transport. If TLS is advertised by a server, the "smtp" transport will
attempt to start a TLS session. However, this can be prevented by
setting "hosts_avoid_tls" (an option of the transport) to a list of
server hosts for which TLS should not be used.

If an attempt to start a TLS session fails for a temporary reason (for
example, a 4xx response to STARTTLS), delivery to this host is not
attempted. If there are alternative hosts, they are tried; otherwise
delivery is deferred. If, on the other hand, the STARTTLS command is
rejected with a 5xx error code, the "smtp" transport attempts to deliver
the message in clear, unless the server matches "hosts_require_tls", in
which case delivery is again deferred unless there are other hosts to
try.

There are a number of options for the "smtp" transport which match the
global TLS options for the server, and have the same names. They are all
expanded before use, with $host and $host_address containing the name
and address of the server to which the client is connected. Forced
failure of an expansion causes Exim to behave as if the relevant option
were unset.

   * "tls_certificate" and "tls_privatekey" provide the client with a
     certificate, which is passed to the server if it requests it. (If
     the server is Exim, it will request it only if
     "tls_verify_certificates" is set.)

   * "tls_verify_certificates" and "tls_verify_ciphers" on the "smtp"
     transport act exactly like their namesakes on the server: they do
     appropriate verification on the server's certificate and the
     negotiated cipher, respectively.


File: exim.info,  Node: Multiple messages on the same TCP/IP connection,  Next: Certificates and all that,  Prev: Configuring Exim to use TLS as a client,  Up: Encrypted SMTP connections using TLS/SSL

Multiple messages on the same TCP/IP connection
===============================================

Exim sends multiple messages down the same TCP/IP connection by
starting up an entirely new delivery process for each message, passing
the socket from one process to the next. This implementation does not
fit well with the use of TLS, because there is quite a lot of state
associated with a TLS connection, not just a socket identification.
Passing all the state information to a new process is not feasible.
Consequently, Exim shuts down an existing TLS session before passing
the socket to a new process. The new process may then try to start a
new TLS session, and if successful, may try to re-authenticate if AUTH
is in use, before sending the next message. If the server is Exim, this
reinitialization works. It is not known if other servers operate
successfully in these circumstances. If they do not, it may be
necessary to set

     batch_max = 1

on the "smtp" transport, to disable multiple messages down a single
TCP/IP connection.


File: exim.info,  Node: Certificates and all that,  Prev: Multiple messages on the same TCP/IP connection,  Up: Encrypted SMTP connections using TLS/SSL

Certificates and all that
=========================

In order to understand fully how TLS works, you need to know about
certificates, certificate signing, and certificate authorities. This is
not the place to give a tutorial, especially as I don't know very much
about it myself. Some helpful introduction can be found in the FAQ for
the SSL addition to Apache, at

     http://www.modssl.org/docs/2.6/ssl_faq.html#ToC24

and other parts of the "modssl" documentation are also helpful, and have
links to further files.

You can create a self-signed certificate using the "req" command
provided with OpenSSL, like this:

     openssl req -x509 -newkey rsa:1024 -keyout file1 -out file2 \
                 -days 9999 -nodes

"file1" and "file2" can be the same file; the key and the certificate
are delimited and so can be identified independently. The -days option
specifies a period for which the certificate is valid. The -nodes
option is important: if you do not set it, the key is encrypted with a
passphrase that you are prompted for, and any use that is made of the
key causes more prompting for the passphrase. This is not helpful if
you are going to use this certificate and key in an MTA, where
prompting is not possible.

A self-signed certificate made in this way is sufficient for testing,
and may be adequate for all your requirements if you are mainly
interested in encrypting transfers, and not in secure identification.


File: exim.info,  Node: Customizing error and warning messages,  Next: The default configuration file,  Prev: Encrypted SMTP connections using TLS/SSL,  Up: Top

Customizing error and warning messages
**************************************

When a message fails to get delivered, or remains on the queue for more
than a configured amount of time, Exim sends a message to the original
sender, or to an alternative configured address. The text of these
messages is built into the code of Exim, but it is possible to change
it, either by adding a single string, or by replacing each of the
paragraphs by text supplied in a file.



* Menu:

* Customizing error messages::
* Customizing warning messages::


File: exim.info,  Node: Customizing error messages,  Next: Customizing warning messages,  Prev: Customizing error and warning messages,  Up: Customizing error and warning messages

Customizing error messages
==========================

If "errmsg_text" is set, its contents are included in the default
message immediately after `This message was created automatically by
mail delivery software.' The string is not expanded. It is not used if
"errmsg_file" is set.

When "errmsg_file" is set, it must point to a template file for
constructing error messages. The file consists of a series of text
items, separated by lines consisting of exactly four asterisks. If the
file cannot be opened, default text is used and a message is written to
the main and panic logs. If any text item in the file is empty, default
text is used for that item.

Each item of text that is read from the file is expanded, and there are
two expansion variables which can be of use here: $errmsg_recipient is
set to the recipient of an error message while it is being created, and
$return_size_limit contains the value of the "return_size_limit" option,
rounded to a whole number.

The items must appear in the file in the following order:

   * The first item is included in the headers, and should include at
     least a "Subject:" header. Exim does not check the syntax of these
     headers.

   * The second item forms the start of the error message. After it,
     Exim lists the failing addresses with their error messages.

   * The third item is used to introduce any text from pipe transports
     that is to be returned to the sender. It is omitted if there is no
     such text.

   * The fourth item is used to introduce the copy of the message that
     is returned as part of the error report.

   * The fifth item is added after the fourth one if the returned
     message is truncated because it is bigger than "return_size_limit".

   * The sixth item is added after the copy of the original message.

The default state ("errmsg_file" unset) is equivalent to the following
file, in which the sixth item is empty. The "Subject:" line has been
split into two here in order to fit it on the page.
------------------------------------------------------------------------


     >>>>>>> .linelength 80em
     
     Subject: Mail delivery failed
       ${if eq{$sender_address}{$errmsg_recipient}{: returning message to sender}}
     ****
     This message was created automatically by mail delivery software.
     
     A message ${if eq{$sender_address}{$errmsg_recipient}{that you sent }{sent by
     
       <$sender_address>
     
     }}could not be delivered to all of its recipients.
     The following address(es) failed:
     ****
     The following text was generated during the delivery attempt(s):
     ****
     ------ This is a copy of the message, including all the headers. ------
     ****
     ------ The body of the message is $message_size characters long; only the first
     ------ $return_size_limit or so are included here.
     ****

------------------------------------------------------------------------

File: exim.info,  Node: Customizing warning messages,  Prev: Customizing error messages,  Up: Customizing error and warning messages

Customizing warning messages
============================

The option "warnmsg_file" can be pointed at a template file for use when
warnings about message delays are created. In this case there are only
three text sections:

   * The first item is included in the headers, and should include at
     least a "Subject:" header. Exim does not check the syntax of these
     headers.

   * The second item forms the start of the warning message. After it,
     Exim lists the delayed addresses.

   * The third item then ends the message.

The default state is equivalent to the file
------------------------------------------------------------------------


     >>>>>>> .linelength 80em
     
     Subject: Warning: message $message_id delayed $warnmsg_delay
     ****
     This message was created automatically by mail delivery software.
     
     A message ${if eq{$sender_address}{$warnmsg_recipients}{that you sent }{sent by
     
       <$sender_address>
     
     }}has not been delivered to all of its recipients after
     more than $warnmsg_delay on the queue on $primary_hostname.
     
     The message identifier is:     $message_id
     The subject of the message is: $h_subject
     The date of the message is:    $h_date
     
     The following address(es) have not yet been delivered:
     ****
     No action is required on your part. Delivery attempts will continue for
     some time, and this warning may be repeated at intervals if the message
     remains undelivered. Eventually the mail delivery software will give up,
     and when that happens, the message will be returned to you.

------------------------------------------------------------------------
except that in the default state the subject and date lines are omitted
if no appropriate headers exist. During the expansion of this file,
$warnmsg_delay is set to the delay time in one of the forms `<n>
minutes' or `<n> hours', and $warnmsg_recipients contains a list of
recipients for the warning message. There may be more than one if there
are multiple addresses with different "errors_to" settings on the
routers/directors that handled them.


File: exim.info,  Node: The default configuration file,  Next: Multiple user mailboxes,  Prev: Customizing error and warning messages,  Up: Top

The default configuration file
******************************

The default configuration file supplied with Exim as
"src/configure.default" is sufficient for a single host with simple
mail requirements. It contains comments about options you might want to
set, but which it lets default, together with the settings described
here.



* Menu:

* Main configuration settings::
* Transport configuration settings::
* Director configuration settings::
* Router configuration settings::
* Default retry rule::
* Rewriting configuration::
* Authenticators configuration::


File: exim.info,  Node: Main configuration settings,  Next: Transport configuration settings,  Prev: The default configuration file,  Up: The default configuration file

Main configuration settings
===========================

There are four explicit options in this section:

     never_users = root

This prevents Exim from ever running as root when performing a local
delivery.  Instead, it runs as `nobody'.

     host_lookup = *

This specifies the sending IP networks for which a DNS reverse lookup
is done, in order to get the host name from the IP address of an
incoming message. The default setting matches all IP addresses. The
host name appears in the log and in messages' "Received:" headers.


     forbid_domain_literals

This locks out the use of `domain literal' addresses such as

     root@[192.168.35.43]

at the syntactic level. Although still specified in the RFCs, such
addresses are not of great relevance in today's Internet, are not
understood by many people, and have been abused by spammers seeking
open relays.


     timeout_frozen_after = 7d

This option causes Exim to abandon frozen messages after they have been
on its queue for a week.

As the "primary_hostname", "qualify_domain", and "local_domains"
options are not specified, they all take the name of the local host, as
obtained by the "uname()" function, as their value.

No relaying is permitted through the host, because neither
"relay_domains" nor "host_accept_relay" is set. See chapter "Other
policy controls on incoming mail" for more details about relay control.


File: exim.info,  Node: Transport configuration settings,  Next: Director configuration settings,  Prev: Main configuration settings,  Up: The default configuration file

Transport configuration settings
================================

Four local transports and one remote transport are defined. The first
one is the remote transport:

     remote_smtp:
       driver = smtp

This transport is used to do external deliveries over SMTP, with default
options.  The first local transport is

     local_delivery:
       driver = appendfile
       file = /var/mail/$local_part
       delivery_date_add
       envelope_to_add
       return_path_add

This is set up to deliver to local mailboxes in a traditional `sticky
bit' directory. Some installations prefer not to set the `sticky bit',
but instead run the delivery under a specific group, with the directory
being writeable by the group. Adding the following options achieves
this:

        group = mail
        mode = 0660

To deliver into files in users' home directories, a setting such as

       file = /home/$local_part/inbox

or

       file = $home/inbox

should be substituted for the default "file" option. The three options
ending in "_add" cause Exim to add three header lines to the message as
it writes it to the mailbox. They can be removed if these headers are
not required. The second local transport is

     address_pipe:
       driver = pipe
       return_output

This transport is used by Exim when a local part that is expanded via
an alias or forward file causes delivery to a pipe.  Any output from
the pipe is returned to the sender of the message. The third local
transport is

     address_file:
       driver = appendfile
       delivery_date_add
       envelope_to_add
       return_path_add

This transport is used by Exim when a local part that is expanded via
an alias or forward file causes delivery to a specified file (by
generating a path name not ending in `/'). The final local transport is

     address_reply:
       driver = autoreply

This transport is used by Exim when a local part that is expanded via a
filter file causes an automatic reply to a message to be generated.


File: exim.info,  Node: Director configuration settings,  Next: Router configuration settings,  Prev: Transport configuration settings,  Up: The default configuration file

Director configuration settings
===============================

Three directors are specified for the default configuration. Note that
the order of director definitions matters. The first director causes
local parts to be checked against the system alias file, which is
searched linearly:

     system_aliases:
       driver = aliasfile
       file = /etc/aliases
       search_type = lsearch
       file_transport = address_file
       pipe_transport = address_pipe

If an alias generates a file or pipe delivery, the "address_file" or
"address_pipe" transport is used, as appropriate.  The second director
comes into play if a local part does not match a system alias:

     userforward:
       driver = forwardfile
       file = .forward
       no_verify
       no_expn
       check_ancestor
     # filter
       file_transport = address_file
       pipe_transport = address_pipe
       reply_transport = address_reply

An attempt is made to look for a file called `.forward' in the home
directory of a local user. However, this director is skipped when
verifying addresses or running an SMTP EXPN command. The
"check_ancestor" option prevents a `.forward' file from turning a login
name back into a previously-handled alias name. The "filter" option is
commented out in the default configuration. Thus `.forward' files are
treated in the conventional manner, but filtering can be enabled by
removing the # character.

If forwarding or filtering generates a file, pipe, or autoreply
delivery, the "address_file", "address_pipe", or "address_reply"
transport is used, as appropriate.  The final director is

     localuser:
       driver = localuser
       transport = local_delivery

This checks that a local part is the login of a local user, and if so,
directs the message to be delivered using the "local_delivery"
transport.


File: exim.info,  Node: Router configuration settings,  Next: Default retry rule,  Prev: Director configuration settings,  Up: The default configuration file

Router configuration settings
=============================

Only one router is defined in the default configuration:

     lookuphost:
       driver = lookuphost
       transport = remote_smtp

Its default settings cause it to look up the domain in the DNS, in
order to determine the host to which a message should be sent, using
the "remote_smtp" transport.


File: exim.info,  Node: Default retry rule,  Next: Rewriting configuration,  Prev: Router configuration settings,  Up: The default configuration file

Default retry rule
==================

A single retry rule is given in the default configuration:

     *    *   F,2h,15m; G,16h,1h,1.5; F,4d,8h

This causes any temporarily failing address to be retried every 15
minutes for 2 hours, then at intervals starting at one hour and
increasing by a factor of 1.5 until 16 hours have passed, then every 8
hours up to 4 days.


File: exim.info,  Node: Rewriting configuration,  Next: Authenticators configuration,  Prev: Default retry rule,  Up: The default configuration file

Rewriting configuration
=======================

There are no rewriting rules in the default configuration file.


File: exim.info,  Node: Authenticators configuration,  Prev: Rewriting configuration,  Up: The default configuration file

Authenticators configuration
============================

No authenticators are specified in the default configuration file. Note
that in order to use SMTP authentication, it is necessary to specify at
least one authenticator in `Local/Makefile'.


File: exim.info,  Node: Multiple user mailboxes,  Next: Using Exim to handle mailing lists,  Prev: The default configuration file,  Up: Top

Multiple user mailboxes
***********************

The wildcard facility of the generic "prefix" and "suffix" options for
directors allows you to configure Exim to permit users to make use of
arbitrary local part prefixes or suffixes in any way they wish.  A
director such as

     userforward:
       driver = forwardfile
       file = .forward
       suffix = -*
       suffix_optional
       filter

runs a user's `.forward' file for all local parts of the form
"*username-**".  Within the filter file the user can distinguish
different cases by testing the variable $local_part_suffix. For example:

     if $local_part_suffix contains -special then
       save /home/$local_part/Mail/special
     endif

If the filter file does not exist, or does not deal with such
addresses, they fall through to subsequent directors, and, assuming no
subsequent use of the "suffix" option is made, they presumably fail.
Thus users have control over which suffixes are valid.

Alternatively, a suffix can be used to trigger the use of a different
`.forward' file - which is the way a similar facility is implemented in
another MTA:

     userforward:
       driver = forwardfile
       file = .forward${local_part_suffix}
       suffix = -*
       suffix_optional
       filter

If there is no suffix, `.forward' is used; if the suffix is "-special",
for example, ".forward-special" is used. Once again, if the appropriate
file does not exist, or does not deal with the address, it is passed on
to subsequent directors, which could, if required, look for an
unqualified `.forward' file to use as a default.


File: exim.info,  Node: Using Exim to handle mailing lists,  Next: Virtual domains,  Prev: Multiple user mailboxes,  Up: Top

Using Exim to handle mailing lists
**********************************

Exim can be used to run simple mailing lists, but for large and/or
complicated requirements, the use of additional specialized mailing
list software is recommended.

The "forwardfile" director can be used to handle mailing lists where
each list is maintained in a separate file, which can therefore be
managed by an independent manager. The "domains" director option can be
used to run these lists in a separate domain from normal mail. For
example:

     lists:
       driver = forwardfile
       domains = lists.ref.book
       no_more
       file = /opt/lists/$local_part
       no_check_local_user
       forbid_pipe
       forbid_file
       errors_to = $local_part-request@lists.ref.book

The domain "lists.ref.book" must appear as one of the domains in the
"local_domains" configuration option. This director is used only when an
address refers to that domain. Because the "no_more" option is set, if
the local part of the address does not match a file in the "/opt/lists"
directory, causing the director to decline, no subsequent directors are
tried, and the whole delivery fails.

The "no_check_local_user" option stops Exim insisting that the local
part is the login id of a local user, and because no user or group is
specified, no check is made on the ownership of the file. The
"forbid_pipe" and "forbid_file" options prevent a local part from being
expanded into a file name or a pipe delivery.

The "errors_to" option specifies that any delivery errors caused by
addresses taken from a mailing list are to be sent to the given address
rather than the original sender of the message. However, before acting
on this, Exim verifies the error address, and ignores it if
verification fails.

For example, using the configuration above, mail sent to
"dicts@lists.ref.book" is passed on to those addresses contained in
"/opt/lists/dicts", with error reports directed to
"dicts-request@lists.ref.book", provided that this address can be
verified.  There could be a file called "/opt/lists/dicts-request"
containing the address(es) of this particular list's manager(s), but
other approaches, such as setting up an earlier director (possibly
using the "prefix" or "suffix" options) to handle addresses of the form
"owner-xxx" or "xxx-request", are also possible.



* Menu:

* Syntax errors in mailing lists::
* NFS-mounted mailing lists::
* Re-expansion of mailing lists::
* Closed mailing lists::


File: exim.info,  Node: Syntax errors in mailing lists,  Next: NFS-mounted mailing lists,  Prev: Using Exim to handle mailing lists,  Up: Using Exim to handle mailing lists

Syntax errors in mailing lists
==============================

If an entry in a forward file contains a syntax error, Exim normally
defers delivery of the entire message. This may not be appropriate when
the list is being maintained automatically from address texts supplied
by users. If the "skip_syntax_errors" option is set on the
"forwardfile" director, it just skips entries that fail to parse,
noting the incident in the log.  If in addition "syntax_errors_to" is
set to a verifyable address, messages about skipped addresses are sent
to it.


File: exim.info,  Node: NFS-mounted mailing lists,  Next: Re-expansion of mailing lists,  Prev: Syntax errors in mailing lists,  Up: Using Exim to handle mailing lists

NFS-mounted mailing lists
=========================

It is not advisable to have list files that are NFS mounted, since the
absence of the mount cannot be distinguished from a non-existent file.
One way round this is to use an "aliasfile" director where the alias
file is local and contains a list of the lists, and each alias
expansion is simply an `include' item to get the list from a separate,
NFS mounted file. If "no_freeze_missing_include" is set for the
"aliasfile" director, an unavailable file then just causes delivery to
be deferred.


File: exim.info,  Node: Re-expansion of mailing lists,  Next: Closed mailing lists,  Prev: NFS-mounted mailing lists,  Up: Using Exim to handle mailing lists

Re-expansion of mailing lists
=============================

Exim remembers every individual address to which a message has been
delivered, in order to avoid duplication, but it normally stores only
the original recipient addresses with a message. If all the deliveries
to a mailing list cannot be done at the first attempt, the mailing list
is re-expanded when the delivery is next tried. This means that
alterations to the list are taken into account at each delivery
attempt, and addresses that have been added to the list since the
message arrived will thus receive a copy of the message, even though it
pre-dates their subscription.

If this behaviour is felt to be undesirable, the "one_time" option can
be set on the "forwardfile" director. If this is done, any addresses
generated by the director that fail to deliver at the first attempt are
added to the message as `top level' addresses, and the parent address
that generated them is marked `delivered'. Thus expansion of the
mailing list does not happen again at the subsequent delivery attempts.
The disadvantage of this is that if any of the failing addresses are
incorrect, correcting them in the file has no effect on pre-existing
messages.

The original top-level address is remembered with each of the generated
addresses, and is output in any log messages. However, any intermediate
parent addresses are not recorded. This makes a difference to the log
only if "log_all_parents" is set, but for mailing lists there is
normally only one level of expansion anyway.


File: exim.info,  Node: Closed mailing lists,  Prev: Re-expansion of mailing lists,  Up: Using Exim to handle mailing lists

Closed mailing lists
====================

The examples so far have assumed open mailing lists, to which anybody
may send mail. It is also possible to set up closed lists, where mail
is accepted from specified senders only. This is done by making use of
the generic "senders" option. The following example uses the same file
for each list, both as a list of recipients and as a list of permitted
senders. In this case, it is necessary to set up a separate director to
handle the `-request' address.

     # Handle mail to xxx-request@lists.ref.book;
     # anybody can mail to this address.
     
     lists_request:
       driver = forwardfile
       domains = lists.ref.book
       suffix = -request
       file = /opt/lists/${local_part}${local_part_suffix}
       no_check_local_user
     
     # Handle mail to xxx@lists.ref.book;
     # only the subscribers to a list may mail to it.
     # Use one_time to prevent multiple expansions.
     
     lists:
       driver = forwardfile
       domains = lists.ref.book
       no_more
       require_files = /opt/lists/$local_part
       senders = lsearch;opt/lists/$local_part
       file = /opt/lists/$local_part
       no_check_local_user
       forbid_pipe
       forbid_file
       one_time
       skip_syntax_errors
       errors_to = $local_part-request@lists.ref.book

The "require_files" option is needed to ensure that the file exists
before trying to search it via the "senders" option; an attempt to
search a non-existent file causes Exim to panic. If the file does not
exist - that is, if the mailing list is unknown, the director declines,
but because "no_more" is set, no further directors are tried, and so
Exim gives up.


File: exim.info,  Node: Virtual domains,  Next: Intermittently connected hosts,  Prev: Using Exim to handle mailing lists,  Up: Top

Virtual domains
***************

There are a number of ways in which virtual domains can be handled in
Exim.  As this seems to be quite a common requirement, some ways of
doing this are described here. These are not the only possibilities.



* Menu:

* All mail to a given host::
* Virtual domains not preserving envelopes::
* Virtual domains preserving envelopes::


File: exim.info,  Node: All mail to a given host,  Next: Virtual domains not preserving envelopes,  Prev: Virtual domains,  Up: Virtual domains

All mail to a given host
========================

Simply sending all mail for a domain to a given host isn't really a
virtual domain; it is just a routing operation that can be handled by a
"domainlist" router.

To send all mail for a domain to a particular local part at a given
host, define the domain as local, then process it with a "smartuser"
director that sets the new delivery address and passes the message to
an "smtp" transport which specifies the host.  Alternatively, use a
"forwardfile" director pointing to a fixed file name; the file can
contain any number of addresses to which each message is forwarded.


File: exim.info,  Node: Virtual domains not preserving envelopes,  Next: Virtual domains preserving envelopes,  Prev: All mail to a given host,  Up: Virtual domains

Virtual domains not preserving envelopes
========================================

A virtual domain that does not preserve the envelope information when
delivering can be handled by an alias file defined for a local domain.
If you are handling a large number of local domains, you can define
them as a file lookup. For example:

     local_domains = your.normal.domain:\
                     dbm;/customer/domains

Where "/customer/domains" is a DBM file built from a source file that
contains just a list of domains:

     # list of virtual domains for customers
     customer1.domain
     customer2.domain

This can be turned into a DBM file by "exim_dbmbuild".

You can then set up a director (see below) to handle the customer
domains, arranging a separate alias file for each domain. A single
director can handle all of them if the names follow a fixed pattern.
Permissions can be arranged so that appropriate people can edit the
alias files. The "domains" option ensures that this director is used
only for the customer domains. The DBM file lookup is cached, so it
isn't too inefficient to do this. The "no_more" setting ensures that if
the lookup fails, Exim gives up on the address without trying any
subsequent directors.

     virtual:
       driver = aliasfile
       domains = dbm;/customer/domains
       no_more
       file = /etc/mail/$domain
       search_type = lsearch

A successful aliasing operation results in a new envelope recipient
address, which is then directed or routed from scratch.


File: exim.info,  Node: Virtual domains preserving envelopes,  Prev: Virtual domains not preserving envelopes,  Up: Virtual domains

Virtual domains preserving envelopes
====================================

If you want to arrange for mail for known local parts at certain
domains to be sent to specific hosts without changing the envelope
recipients of messages, then the following is one way of doing it.

Set up the domains as local, and create an "aliasfile" director for
them, as above, but in addition, specify a transport for the director:

     virtual:
       driver = aliasfile
       domains = dbm;/customer/domains
       transport = virtual_smtp
       no_more
       file = /etc/mail/$domain
       search_type = lsearch

Each domain has its own alias file, but the provision of a transport
means that this is used purely as a check list of local parts. The data
portion of each alias is not used.

The transport has to look up the appropriate host to which the message
must be sent:

     virtual_smtp:
       driver = smtp
       hosts = ${lookup{$domain}dbm{/virtual/routes}{$value}fail}

The file "/virtual/routes" contains lines of the form

     customer1.domain:  cust1.host
     customer2.domain:  cust2.host

and the messages get delivered with RCPT (the envelope) containing the
original destination address (for example,
"postmaster@customer1.domain"). In fact, you could use the same file
for "/virtual/routes" and "/customer/domains", since the lookup on the
latter doesn't make any use of the data - it's just checking that the
file contains the key.


File: exim.info,  Node: Intermittently connected hosts,  Next: Verification of incoming mail,  Prev: Virtual domains,  Up: Top

Intermittently connected hosts
******************************

It is becoming quite common (because it is cheaper) for hosts to
connect to the Internet periodically rather than remain connected all
the time. The normal arrangement is that mail for such hosts
accumulates on a system that is permanently connected.

Exim was designed for use on permanently connected hosts, and so it is
not particularly well-suited to use in an intermittently connected
environment.  Nevertheless there are some features that can be used.



* Menu:

* Exim on the upstream host::
* Exim on the intermittently connected host::
* Handling many intermittently connected hosts::


File: exim.info,  Node: Exim on the upstream host,  Next: Exim on the intermittently connected host,  Prev: Intermittently connected hosts,  Up: Intermittently connected hosts

Exim on the upstream host
=========================

If the `holding system' is running Exim, it should be configured with a
long retry period for the intermittent host. For example:

     cheshire.wonderland.fict.book    *   F,5d,24h

This stops a lot of failed delivery attempts from occurring, but Exim
remembers which messages it has queued up for that host. Once the
intermittent host comes online, forcing delivery of one message (either
by using the -M or -R options, or by using the ETRN SMTP command - see
"smtp_etrn_hosts" and section "The ETRN command" in chapter "SMTP
processing") causes all the queued up messages to be delivered, often
down a single SMTP connection. While the host remains connected, any new
messages get delivered immediately.

If the connecting hosts do not have fixed IP addresses, that is, if a
host is issued with a different IP address each time it connects,
Exim's retry mechanisms on the holding host get confused, because the
IP address is normally used as part of the key string for holding retry
information. This can be avoided by unsetting
"retry_include_ip_address" on the "smtp" transport.  Since this has
disadvantages for permanently connected hosts, it is best to arrange a
separate transport for the intermittently connected ones.


File: exim.info,  Node: Exim on the intermittently connected host,  Next: Handling many intermittently connected hosts,  Prev: Exim on the upstream host,  Up: Intermittently connected hosts

Exim on the intermittently connected host
=========================================

The value of "smtp_accept_queue_per_connection" should probably be
increased, or even set to zero (that is, disabled) on the
intermittently connected host, so that all incoming messages down a
single connection get delivered immediately.

Mail waiting to be sent from an intermittently connected host will
probably not have been routed, since without a connection DNS lookups
are not possible.  This means that if a normal queue run is done at
connection time, each message is likely to be sent in a separate SMTP
session. This can be avoided by starting the queue run with a command
line option beginning with -qq instead of -q. In this case, the queue
is scanned twice. In the first pass, routing is done but no deliveries
take place. The second pass is a normal queue run; since all the
messages have been previously routed, those destined for the same host
are likely to get sent as multiple deliveries in a single SMTP
connection.


File: exim.info,  Node: Handling many intermittently connected hosts,  Prev: Exim on the intermittently connected host,  Up: Intermittently connected hosts

Handling many intermittently connected hosts
============================================

Leaving mail for intermittently connected hosts on the main queue of a
holding system as suggested above does not scale very well. Two
different kinds of waiting message are being mixed up in the same queue
- those that cannot be delivered because of some temporary problem, and
those that are waiting for their destination host to connect. This
makes it hard to manage the queue, as well as wasting resources,
because each queue runner scans the entire queue.

A better approach is to separate off those messages that are waiting
for an intermittently connected host. This can be done by using a
separate version of Exim that stores only those messages, or by
delivering such messages into local files in batch SMTP, `mailstore',
or other envelope-preserving format, from where they are transmitted by
other software when their destination connects.  This makes it easy to
collect all the mail for one host in a single directory, and to apply
local timeout rules on a per-message basis if required.


File: exim.info,  Node: Verification of incoming mail,  Next: Other policy controls on incoming mail,  Prev: Intermittently connected hosts,  Up: Top

Verification of incoming mail
*****************************

Exim always checks the syntax of SMTP commands, and rejects any that are
invalid. There are a number of options that cause Exim to verify the
semantic validity of the data in an incoming SMTP message. Verification
failures can cause the message to be rejected, or they can just be
logged. Other types of control over incoming mail are discussed in
subsequent chapters. The -bh command line option can be used to run
fake SMTP sessions for the purpose of testing verification options.



* Menu:

* Host verification::
* Sender verification::
* Sender verification with callback::
* Fixing bad senders::
* Header verification::
* Receiver verification::


File: exim.info,  Node: Host verification,  Next: Sender verification,  Prev: Verification of incoming mail,  Up: Verification of incoming mail

Host verification
=================

The name of the sending host is looked up using "gethostbyaddr()" if
its IP address matches "host_lookup" (which is unset in the Exim
binary, but in the default configuration file is set to match all
hosts). In some environments this might involve an expensive DNS
lookup, so some sites may wish to disable it. However, an SMTP server
for local desktop systems (which are frequently misconfigured) can
normally look up their host names cheaply. This improves the contents
of Exim's logs by including the correct host names.

Even if its address doesn't match "host_lookup", a sending host's real
name is looked up from its IP address if the argument it provides for
the HELO or EHLO command is the local host's own name, or the name of
one of its local domains, which seems to be a fairly common
misconfiguration.

A host name that is obtained from looking up the sender's IP address is
placed in the $sender_host_name variable. If no lookup was done, or if
the lookup failed, that variable is left empty. Failure to look up the
sending host's name is not of itself an error, nor is it by default an
error for the name given in the HELO or EHLO command (which is placed
in $sender_helo_name) to be different.

The RFCs specifically state that mail should not be refused on the
basis of the content of the HELO or EHLO commands. However, there are
installations that do want to be strict in this area, and to support
them, Exim has the "helo_verify" option. Even when this is not set,
Exim checks the syntax of the commands, and rejects them if there are
syntax errors. It can be made less strict by unsetting
"helo_strict_syntax" (which allows underscores to get through) or by
setting "helo_accept_junk_hosts" (which permits certain hosts to send
any old junk).

When "helo_verify" is set, a HELO or EHLO command must precede any MAIL
commands in an incoming SMTP connection. If there wasn't one, all MAIL
commands are rejected with a permanent error code. In addition, the
argument supplied by HELO or EHLO is verified. If it is in the form of
a literal IP address in square brackets, it must match the actual IP
address of the sending host. If it is a domain name, the sending host's
name is looked up from its IP address (whether or not it matches
"host_lookup") and compared against it. If the comparison fails, the IP
addresses associated with the HELO or EHLO name are looked up using
"gethostbyname()" and compared against the sending host's IP address.
If none of them match, the HELO or EHLO command is rejected with a
permanent error code, and an entry is written in the main and reject
logs.


File: exim.info,  Node: Sender verification,  Next: Sender verification with callback,  Prev: Host verification,  Up: Verification of incoming mail

Sender verification
===================

When "sender_verify" is set, Exim checks the senders of incoming SMTP
messages, that is, the addresses given in the SMTP MAIL commands.  This
does not apply to batch SMTP input by default, but "sender_verify_batch"
can be set true if it is required.  The check is performed by running
the same verification code as is used when Exim is called with the -bvs
option, that is, by running the directors and routers in verify mode.

A dilemma arises when a local address is expanded by aliasing or
forwarding: should verification continue with the generated addresses,
or should the successful expansion of the original address be enough to
verify it? Exim (since release 3.20) takes the following pragmatic
approach:

   * When an incoming address is aliased to just one child address, in
     an "aliasfile" or a "smartuser" director (but not for
     "forwardfile"), verification continues with the child address, and
     if that fails to verify, the original verification also fails.

This seems the most reasonable behaviour for the common use of aliasing
as a way of directing different local parts to the same mailbox. It
means, for example, that a pair of alias entries of the form

     A.Wol:   aw123
     aw123:   :fail: Gone away, no forwarding address

work as expected, with both local parts causing verification failure.
On the other hand, when an alias generates more than one address, the
behaviour is more like a mailing list, where the existence of the alias
itself is sufficient for verification.

The sender verification check is performed when the MAIL command is
received. If the address cannot immediately be verified (typically
because of DNS timeouts), a temporary failure error response (code 451)
is given after the data for the message has been received. It is
delayed until this time so that the message's headers can be logged.
However, if "sender_try_verify" is set, the sender is accepted with a
warning message after a temporary verification failure.

Exim remembers temporary sender verification errors in a hints database.
Subsequent temporary errors for the same address from the same host
within 24 hours cause a 451 error after MAIL instead of after the data.
This reduces the data on the reject log and also the amount repeatedly
transferred over the net.

If "sender_verify_max_retry_rate" is set greater than zero, and the
rate of temporary rejection of a specific incoming sender address from
a specific host, in units of rejections per hour, exceeds it, the
temporary error is converted into a permanent verification error. This
should help in stopping hosts hammering too frequently with temporarily
failing sender addresses. The default value of the option is 12, which
means that a sender address that has a temporary verification error
more than once every 5 minutes will soon get permanently rejected. Once
permanent rejection has been triggered, subsequent temporary failures
will all cause permanent errors, until there has been an interval of at
least 24 hours since the last failure. After 24 hours, the hint expires.

What happens if verification fails with a permanent error depends on the
setting of the "sender_verify_reject" option. If it is set (the
default) then the message is rejected. Otherwise a warning message is
logged, and processing continues.

Because remote postmasters always want to see the message headers when
there is a problem, Exim does not give an error response immediately a
sender address fails, but instead it reads the data for the message
first. The headers of rejected messages are written to the reject log,
for use in tracking down the problem or tracing mail abusers. Up to
three envelope recipients are also logged with the headers.

Unfortunately, there are a number of mailers in use that treat any SMTP
error response given after the data has been transmitted as a temporary
failure. Exim sends code 550 when it rejects a message because of a bad
sender, and RFC 821 is quite clear in stating that all codes starting
with 5 are always `permanent negative completion' replies. However, it
does not give any guidance as to what should be done on receiving such
replies, and some mailers persist in trying to send messages when they
receive such a code at the end of the data.

To get round this, Exim keeps a database in which it remembers the bad
sender address and host name when it rejects a message. If the same
host sends the same bad sender address within 24 hours, Exim rejects
the message at the MAIL command, before it reads the data for the
message. This should prevent the sender from trying to send the message
again, but there seem to be plenty of broken mailers out there that do
keep on trying, sometimes for days on end.

In an attempt to shut such MTAs up, if the same host sends the same bad
sender for a third time within 24 hours, MAIL is accepted, but all
subsequent RCPT commands are rejected with a 550 error code. This means
`unknown user' and if a remote mailer doesn't treat that as a hard
error, it is very seriously broken.

The "sender_verify_hosts" option can be used to restrict hosts and RFC
1413 idents for which sender verification is not applied. If a cluster
of hosts all check incoming external messages, there is no need to
waste effort checking mail sent between them. For example:

     sender_verify_hosts = ! *.ref.book : ! exim@mailer.fict.book


File: exim.info,  Node: Sender verification with callback,  Next: Fixing bad senders,  Prev: Sender verification,  Up: Verification of incoming mail

Sender verification with callback
=================================

When Exim verifies a remote sender address by running it through the
routers, as described above, it verifies the domain, but is unable to
do any checking of the local part. There are situations where some
means of verifying the local part is desirable, and this can be setup
by configuring Exim to use an SMTP "callback". If the domain in the
remote address verifies successfully when calling back is enabled, Exim
makes an SMTP call to the hosts to which the sender's domain resolves,
and tests the address as if it were the recipient of a bounce message.
Specifically, it sends

     HELO <primary host name>
     MAIL FROM:<>
     RCPT TO:<the address to be tested>
     QUIT

If the response to the RCPT command is a 2xx code, the verification
succeeds. If it is 5xx, the verification fails. For anything else, and
in cases when Exim cannot contact any of the relevant hosts,
verification fails with a temporary error code.

Callback verification occurs only if the sending host matches
"sender_verify_hosts_callback" (in addition to "sender_verify_hosts"),
and the sender's domain matches "sender_verify_callback_domains". Both
of these options default unset. There is also an option called
"sender_verify_callback_timeout" which sets a timeout for connecting
and for each command. It defaults to 30 seconds. Callback verification
is expensive, and not recommended for general use, especially on busy
hosts. Two cases where it might be useful are:

   * On a small host that handles only a few messages a day, to keep
     out junk with valid domains but invalid local parts in the
     senders, something that is commonly encountered in spam messages.
     For this you would set

          sender_verify_hosts_callback = *
          sender_verify_callback_domains = *

   * On a corporate gateway, to check sender addresses in domain(s)
     that are `yours' in some sense, but not local (in the Exim sense).
     This could be restricted to messages received from your on-site
     hosts.


File: exim.info,  Node: Fixing bad senders,  Next: Header verification,  Prev: Sender verification with callback,  Up: Verification of incoming mail

Fixing bad senders
==================

It is unfortunately the case that lots of messages are sent out onto the
Internet with invalid senders. In some cases, the message itself
contains a valid return address in one of its headers. If the
"sender_verify_fixup" option is set as well as "sender_verify", Exim
does not reject a message if the sender is invalid, provided it can
find a "Sender:", "Reply-To:", or "From:" header containing a valid
address. Instead, it replaces the sender with the valid address, and
records the fact that it has done so by adding a header of the form:

     X-BadReturnPath: <invalid address> rewritten using <name> header

If there are several occurrences of any of the relevant headers, they
are all checked. If any `Resent-' headers exist, it is those headers
that are checked rather than the original ones.

The fixup happens for both permanent and temporary errors. This covers
the case when the bad addresses refer to some DNS zone whose
nameservers are unreachable. This approach is, of course, fixing the
symptom and not the disease. If "sender_verify_fixup" is set when
"sender_verify_reject" is false, Exim does not modify the message, but
records in the log the fixup it would have made.


File: exim.info,  Node: Header verification,  Next: Receiver verification,  Prev: Fixing bad senders,  Up: Verification of incoming mail

Header verification
===================

Exim's sender verification options can be used to block messages with
bad envelope senders. However, if a message arrives with a null
envelope sender, that is, if the SMTP command was

     MAIL FROM:<>

then Exim has nothing to check, and is forced to accept the message
(unless it fails another check, of course). If
"headers_sender_verify_errmsg" is set, then for messages that have null
senders (purporting to be mail delivery error messages), Exim does some
checking of the RFC 822 headers. It looks for a valid address in the
"Sender:", "Reply-To:", and "From:" headers, and if one cannot be
found, the message is rejected, unless "headers_checks_fail" is false,
in which case it just makes a warning entry in the reject log.

If there are several occurrences of any of the relevant headers, they
are all checked. If any `Resent-' headers exist, it is those headers
that are checked rather than the original ones.

Unfortunately, because it has to read the message before doing this
check, the rejection happens after the end of the data, and it is known
that some mailers do not treat hard (5xx) errors correctly at this
point - they keep the message on their spools and try again later, but
that is their problem, though it does waste some resources.

The option "headers_sender_verify" is also available. It insists on
there being a valid "Sender:", "Reply-To:", or "From:" header on all
incoming SMTP messages, not just those with null senders.

The "sender_verify_hosts" option applies to both of these header
checking options as well as to checks on envelope senders
("sender_verify").

A common spamming ploy is to send syntactically invalid headers such as

     To: @

The option "headers_check_syntax" causes Exim to check the syntax of all
headers that can contain lists of addresses ("Sender:", "From:",
"Reply-To:", "To:", "Cc:", and "Bcc:") on all incoming messages (both
local and SMTP). This is a syntax check only. Like the
"headers_sender_verify" options, the rejection happens after the end of
the data, and it is also controlled by "headers_checks_fail"; if that
is false, a bad message is accepted, with a warning in the reject log.


File: exim.info,  Node: Receiver verification,  Prev: Header verification,  Up: Verification of incoming mail

Receiver verification
=====================

By default, Exim just checks the syntax of addresses given in the SMTP
RCPT command. This minimizes the time required for an SMTP message
transfer, and also makes it possible to provide special processing for
unknown local parts in local domains, by using a "smartuser" director
to pass messages with unknown local parts to a script or to another
host.

Some installations prefer to check receiver addresses as they are
received. If the "receiver_verify" option is set, the same code that is
used by the -bv option is used to check incoming addresses from remote
hosts that match "receiver_verify_hosts", whose default setting is to
match all hosts.  Verification consists of running the directors and
routers in verify mode. As in the case of sender verification, when an
incoming address is aliased to just one child address, in an
"aliasfile" or a "smartuser" director (but not for "forwardfile"),
verification continues with the child address, and if that fails to
verify, the original verification also fails.

When verification fails, a permanent negative response is given to the
RCPT command. If there is a temporary failure, a temporary error is
given, unless "receiver_try_verify" is set, in which case the address
is accepted.

It is possible to restrict the addresses that are verified to certain
domains by setting "receiver_verify_addresses", and receiver
verification can also be made conditional on the sender address by
setting "receiver_verify_senders".  All of these options operate only
when "receiver_verify" or "receiver_try_verify" is set.


File: exim.info,  Node: Other policy controls on incoming mail,  Next: System-wide message filtering,  Prev: Verification of incoming mail,  Up: Top

Other policy controls on incoming mail
**************************************

Exim provides a number of facilities for controlling incoming mail from
remote hosts, in addition to the verification options described in the
previous chapter. These controls can be used to stop unwanted messages
getting into your machine. After a message has been accepted, the
filtering mechanism described in chapter "System-wide message
filtering" can be used to check it before going ahead with delivery.

An MTA is said to "relay" a message if it receives it from some host and
delivers it directly to another host as a result of a remote address
contained within it. Expanding a local address via an alias or forward
file and then passing the message on to another host is not relaying,
but a re-direction as a result of the `percent hack' is. There are
special options for controlling which remote hosts may use the local
host as a relay.

The options described in this chapter control three stages of checking
that are applied to an incoming SMTP message:

  1. At the start of an SMTP connection, a check on the remote host is
     made, leading to one of the following conclusions:

       a. No mail whatsoever is acceptable from the remote host.

       b. The remote host is permitted to send messages to local
          recipients only, but is not permitted to use the local host
          as a relay.

       c. The remote host is permitted to send messages to local
          recipients, and can also use the local host as a relay to
          certain specified domains only.

       d. The remote host is permitted to send mail to any recipient.

     If the host is completely unacceptable, the SMTP connection may be
     rejected immediately, or (depending on the configuration) the
     message may be refused later on by a rejection at the end of the
     message (so the headers can be logged) or by rejecting every
     recipient.

  2. The message's sender, which is obtained from the MAIL command, is
     checked. Again there is a choice of immediate rejection, or
     delayed rejection of all recipients.

  3. Unless there are no controls on relaying, the recipient address in
     each RCPT command is checked.

These checks are all in addition to any verification that may be
enabled. The following sections give details of the various checking
options.  The -bh command line option can be used to run fake SMTP
sessions for the purpose of testing them.



* Menu:

* Host checking using RBL::
* Other host checking::
* Sender checking::
* Control of relaying::
* Customizing prohibition messages::


File: exim.info,  Node: Host checking using RBL,  Next: Other host checking,  Prev: Other policy controls on incoming mail,  Up: Other policy controls on incoming mail

Host checking using RBL
=======================

The Realtime Blackhole List (RBL) is a black list of hosts that is
maintained in the DNS. See http://mail-abuse.org/rbl/ for the
background to this. Since the RBL was created, a number of other
similar lists (DUL, ORBS, RRSS, IMRSS) have sprung up. These all
operate in the same way. If the "rbl_domains" option is set, Exim looks
up inverted incoming IP addresses in each of the given domains,
provided the remote host matches "rbl_hosts" (whose default is to match
all hosts). For example, if the setting is

     rbl_domains = blackholes.mail-abuse.org:dialups.mail-abuse.org

and an SMTP call is received from the host whose IP address is
192.168.8.1, then DNS lookups for address records for

     1.8.168.192.blackholes.mail-abuse.org
     and
     1.8.168.192.dialups.mail-abuse.org

are done. Each domain in "rbl_domains" can be followed by `/warn' or
`/reject' to specify what is to be done when a matching DNS record is
found, for example:

     rbl_domains = blackholes.mail-abuse.org/warn : \
                   dialups.mail-abuse.org/reject

The action for domains without either of these is controlled by
"rbl_reject_recipients", which implies `/reject' when set.  If a lookup
times out or otherwise fails to give a decisive answer, the address is
not blocked (by that entry in the list).

Two further options, in addition to `/warn' and `/reject', are
available:

   * `/accept' allows RBL-type lookups to be used for `white lists' as
     well as black lists. The message is accepted from a host that
     matches an `/accept' item, and no further RBL domains are
     considered.  Earlier `/warn' entries may have already added
     warning headers.

   * `/skiprelay' causes that particular RBL domain to be skipped if
     the calling host matches "host_accept_relay". In other words, if
     the host has been listed as one that is permitted to relay, no RBL
     check is done for it.

The original RBL just used the address 127.0.0.1 on the right hand side
of the addresses records, but some other lists use a number of
different values. The ORBS database, for example, uses different
addresses to denote different types of open relay, and you might want
to block on some but not on others. The current values are 127.0.0.2
for a confirmed open relay, 127.0.0.3 for a manual entry, and 127.0.0.4
for a `netblock'.

By adding an equals sign and an IP address after an RBL domain name,
you can restrict its action to DNS records with a matching right hand
side. For example,

     rbl_domains = relays.orbs.org=127.0.0.2/reject

rejects only those hosts that yield 127.0.0.2 from the ORBS database.
More than one address may be given, using a comma as a separator. These
are alternatives - if any one of them matches, the RBL entry operates.
If there are no addresses, any address record is considered to be a
match.

When a hosts matches an RBL item, warning consists of writing a message
to the main and reject logs, and, if "rbl_warn_header" is true (the
default), adding an "X-RBL-Warning:" header to the message. This can be
detected later by system or user filter files. If a host appears in
several RBL lists, more than one such header may be added to a message.

Rejection is done by refusing all recipients, that is, by giving
permanent error returns to all RCPT commands, unless the message's
sender is listed in "recipients_reject_except_senders", or the
recipient is listed in "recipients_reject_except". It is fairly common
to set

     recipients_reject_except = postmaster@your.domain

to allow your host to accept mail to the postmaster from blacklisted
hosts.  "X-RBL-Warning:" headers are added to messages that get
accepted as a result of an exception list.

If a TXT record associated with the host is found in the RBL domain, its
contents are returned as part of the 550 rejection message, unless
"prohibition_message" is set (see section "Customizing prohibition
messages"), in which case a locally-specified message is used.  This
can include any TXT data by referring to $rbl_text. It may also
refererence the RBL domain that caused the rejection by referring to
$rbl_domain (and, of course, the incoming host IP address is available
in $sender_host_address).


File: exim.info,  Node: Other host checking,  Next: Sender checking,  Prev: Host checking using RBL,  Up: Other policy controls on incoming mail

Other host checking
===================

Exim rejects incoming SMTP calls from any host that matches
"host_reject".  For example:

     host_reject = ! xxx.yy.zz : *.yy.zz : ! *.zz

rejects mail from any host outside the "zz" domain, and all hosts in the
"yy.zz" domain, except for "xx.yy.zz". The use of wildcarded names
implies a reverse DNS lookup of the incoming IP address. This can be
avoided by using IP addresses. See section "Host lists" in chapter "The
Exim configuration file" for details.

Calls are rejected as a result of these options by sending a 5xx error
code as soon as the connection is received. Since this does not relate
to any particular message, the remote host is likely to keep on trying
to send mail (possibly to an alternative MX host) until it times out.
This may be what is wanted in some circumstances (for example, you want
temporarily to hold back all incoming mail from some host), but when
dealing with incoming spam, for example, one normally wants messages to
be rejected once and for all, and in this case,
"host_reject_recipients" should be used instead of "host_reject".

A call from a host which matches "host_reject_recipients" is not
rejected at the start; instead, every RCPT command is subsequently
rejected, which should cause the remote MTA to cease trying to deliver
the message. This style of blocking also has the advantage of catering
for exceptions for certain recipients, via the
"recipients_reject_except" option. This is commonly set to the local
postmaster address.


File: exim.info,  Node: Sender checking,  Next: Control of relaying,  Prev: Other host checking,  Up: Other policy controls on incoming mail

Sender checking
===============

Incoming messages can be rejected on the basis of the sender address,
as given in the MAIL command. A list of senders to reject is set by the
"sender_reject" configuration option; see its description in chapter
"Main configuration" for details.

Some MTAs continue to try to deliver a message even after receiving a
5xx error code for MAIL. The alternative configuration option
"sender_reject_recipients" is provided for use in such cases. It
accepts the MAIL command but rejects all subsequent RCPT commands.


File: exim.info,  Node: Control of relaying,  Next: Customizing prohibition messages,  Prev: Sender checking,  Up: Other policy controls on incoming mail

Control of relaying
===================

Two kinds of relaying exist, which are termed `incoming' and `outgoing'.
A host which is acting as a gateway or an MX backup is concerned with
incoming relaying from arbitrary hosts to a specific set of domains. On
the other hand, a host which is acting as a smart host for a number of
clients is concerned with outgoing relaying from those clients to the
Internet at large. Often the same host is fulfilling both functions, as
illustrated in the diagram below, but in principle these two kinds of
relaying are entirely independent, and are therefore controlled by
separate options. What is not wanted is the transmission of mail from
arbitrary remote hosts through your system to arbitrary domains.

        --------------    -----------
        | Arbitrary  |    |Arbitrary|
        |remote hosts|    | domains |
        --------------    -----------
      I       v                ^       O
      n       v                ^       u
      c    ---v----------------^---    t
      o    |  v     Local      ^  |    g
      m    |  v      host      ^  |    o
      i    ---v----------------^---    i
      n       v                ^       n
      g       v                ^       g
           Specific         Specific
           domains           hosts

Incoming relaying is controlled by restricting the domains to which an
arbitrary host may send via the local host; this is done by setting
"relay_domains". For example, you use this option to list the domains
that your host is an MX backup for. Outgoing relaying is controlled by
restricting the set of hosts which may send via the local host to an
arbitrary domain, by setting "host_accept_relay". For example, a
delivery server uses this option to list its client hosts.

Checks for unwanted relaying are made on the domains of recipient
addresses in messages received from other hosts. This is done at the
time of the RCPT command in the SMTP dialogue. The first check is
whether the address would cause relaying at all: if its domain matches
something in "local_domains" then it is destined to be handled on the
local host as a local address, and relaying is not involved.

This includes the case of addresses such as ""x@y"@z" where "z" is a
local domain, which are sometimes used in an attempt to bypass relaying
restrictions. Exim treats such addresses as having a local part "x@y" -
it does not strip off the local domain and treat "x@y" as an entirely
new address. Assuming that "x@y" is not a valid local part, this means
that the address is rejected, either at SMTP time if "receiver_verify"
is set, or later when Exim tries to deliver to it.  Addresses of the
form ""x%y"@z" are treated in the same way, unless the `percent hack'
has been enabled by setting "percent_hack_domains". In this case, the
new address (constructed from the local part by changing the % to an @)
is treated as an incoming address, and its domain is re-tested to ensure
that it complies with any relaying restrictions.

When the relevant domain is not in "local_domains", there is first a
check for legitimate incoming relaying, by seeing if it matches
"relay_domains", or, when "relay_domains_include_local_mx" is set, if
it is a domain with an MX record pointing to the local host. If it does
match, this is an acceptable incoming relay, and it is permitted to
proceed. For example, if the FooBar company has a firewall machine
through which all mail from external hosts must pass, and this
machine's configuration contains

     local_domains = foobar.com
     relay_domains = *.foobar.com

then mail from external hosts is rejected, unless it is for a domain
ending in "foobar.com".

Warning: Turning on the "relay_domains_include_local_mx" option opens
your server to the possibility of abuse in that anyone with access to a
DNS zone can list your server in a secondary MX record as a backup for
their domain without your permission. This is not a huge exposure
because firstly, it requires the cooperation of a hostmaster to set up,
and secondly, since their mail is passing through your server, they run
the risk of your noticing and (for example) throwing all their mail
away.

If a recipient address is neither for a local domain nor an incoming
relay, it must be an outgoing relay, and it is accepted only if the
sending host is permitted to relay to arbitrary domains, and if the
sender address is acceptable. The set of hosts that are permitted to
relay is specified by "host_accept_relay". For example, if the FooBar
company's IP network is 172.16.213.0/24, and all hosts on that network
send their outgoing mail via the firewall machine, its configuration
should contain

     host_accept_relay = 172.16.213.0/24

in order to allow only the internal hosts to use it as a relay to
arbitrary domains.  Exim does not make an automatic exception for the
loopback IP address, so if you want to permit relaying from processes
on the local host using this method, you need to include 127.0.0.1 in
the relay list. Some user agents, notably MH and NMH, send mail by
connecting to the loopback address on the local host.

The option "host_auth_accept_relay" is similar to "host_accept_relay",
except that any client host matching one of its items is permitted to
relay only if it has successfully authenticated. This is independent of
whether or not it matches "auth_hosts". You can set
"host_auth_accept_relay" only if Exim has been compiled to support SMTP
authentication. Chapter "SMTP authentication" contains more details.

In addition to the tests on the host, if "sender_address_relay" is set,
the sender's address from the MAIL command must match one of its
patterns to allow outgoing relaying to an arbitrary domain. Also, if
there are any rewriting rules with the `X' flag set, such an address is
rewritten using those rules, and the result (if different) must verify
successfully. See section "The additional relay checking flag" in
chapter "Address rewriting" for an example of how this can be used.

Normally, therefore, both the host and the sender must be acceptable
before an outgoing relay is allowed to proceed. However, if
"relay_match_host_or_sender" is set, an address is accepted for outgoing
relaying if either the host or the sender is acceptable. Of course,
sender addresses can easily be forged, but the sender check does mean
you can prevent some kinds of unwanted mail from going through your
host.

All three options, "relay_domains", "host_accept_relay", and
"host_auth_accept_relay", are unset by default, which means that no
relaying of any kind is enabled. This does not prevent a local user
from setting up forwarding to some external system, but it does prevent
the `percent hack' from relaying to arbitrary domains even when
"percent_hack_domains" is set.

As all the relay checking is done at RCPT time on incoming messages, the
directors and routers are not involved. Depending on the configuration
of these drivers, an address that appears to be remote to the relay
checking code (that is, its domain does not match "local_domains") may
nevertheless end up being delivered locally, and similarly an
apparently local address may end up being delivered to some other host.

None of the relay checking applies when mail is passed to Exim locally
using the -bm, -bs or -bS options, but it does apply when -bs is used
from "inetd".

Exim does not attempt to fully qualify domains at RCPT time. If an
incoming message contains a domain which is not fully qualified, it is
treated as a non-local, non-relay domain (unless partial domains are
included in "local_domains" or "relay_domains", but this is not
recommended). The use of domains that are not fully qualified is
non-standard, but it is a commonly encountered usage when an MTA is
being used as a smart host by some remote UA.  In this situation, it
would be usual to permit the UA host to relay to any domain, so in
practice there is not normally a problem.


File: exim.info,  Node: Customizing prohibition messages,  Prev: Control of relaying,  Up: Other policy controls on incoming mail

Customizing prohibition messages
================================

It is possible to add a site-specific message to the error response that
is sent when an incoming SMTP command fails for policy reasons, for
example if the sending host is in a host reject list. This is done by
setting the option "prohibition_message", which causes one or more
additional response lines with the same error code and a multiline
marker to be output before the standard response line. For example,
setting

     prohibition_message = contact postmaster@my.site for details

causes the response to a RCPT command for a blocked recipient to be

     550-contact postmaster@my.site for details
     550 rejected: administrative prohibition

The string is expanded, and so it can do file lookups if necessary. If
it ends up as an empty string, no additional response is transmitted.
To make it possible to distinguish between the several different types
of administrative rejection, the variable $prohibition_reason is set to
a characteristic text string in each case. The possibilities are as
follows:

     host_accept_relay          the host is not in an "accept_relay" list
     host_reject                the host is in a reject list
     host_reject_recipients     the host is in a "reject_recipients" list
     rbl_reject                 the host is rejected by an RBL domain
     receiver_verify            receiver verification failed
     sender_relay               the sender is not in a sender relay list
     sender_reject              the sender is in a reject list
     sender_reject_recipients   the sender is in a "reject_recipients" list
     sender_verify              sender verification failed

In addition, if "relay_match_host_or_sender" is set, there is

     sender+host_accept_relay  the sender is not in a sender relay list
                                 and the host is not in an accept relay list

For example, if the configuration contains

     prohibition_message = ${lookup{$prohibition_reason}lsearch\
       {/etc/exim/reject.messages}{$value}}

and the file "/etc/exim/reject.messages" contains (inter alia)

     host_accept_relay:  host not in relay list

then a response to a relay attempt might be

     550-host not in relay list
     550 relaying to <santa@northpole.com> prohibited by administrator

Because some administrators may want to put in quite long messages, and
it isn't possible to get newlines into the text returned from an
lsearch lookup, Exim treats the vertical bar character as a line
separator in this text. If you want the looked up text to be
re-expanded, you can use the "expand" operator.  For example, the
setting

     prohibition_message = ${lookup{$prohibition_reason}lsearch\
       {/etc/exim/reject.messages}{${expand:$value}}}

when used with a file entry of the form

     host_accept_relay:  Host $sender_fullhost is not permitted to
                         relay |through $primary_hostname.

might produce

     550-Host that.host.name [111.222.3.4] is not permitted to relay
     550-through this.host.name.
     550 relaying to <penguins@southpole.com> prohibited by administrator

In the case of an RBL rejection, $rbl_domain contains the RBL domain
that caused the rejection during the expansion of
"prohibition_message", and $rbl_text contains the contents of any
associated TXT record. In all cases, $sender_host_address contains the
IP address of the calling host.


File: exim.info,  Node: System-wide message filtering,  Next: SMTP processing,  Prev: Other policy controls on incoming mail,  Up: Top

System-wide message filtering
*****************************

The previous chapters describe checks that can be applied to messages
before they are accepted by a host. There are also mechanisms for
checking messages once they have been received, but before they are
delivered. If a system message filter is defined, it is run each time a
delivery process is started for a message. It is also possible to run a
centrally-defined filter file once for each local address, as part of
the directing for that address.



* Menu:

* The system message filter::
* Additional commands for system filters::
* Per-address filtering::


File: exim.info,  Node: The system message filter,  Next: Additional commands for system filters,  Prev: System-wide message filtering,  Up: System-wide message filtering

The system message filter
=========================

The system message filter operates in a similar manner to users' filter
files, but it is run just once per message (however many recipients is
has) at the start of a delivery attempt, before any routing or
directing is done. If a message fails to be completely delivered at the
first attempt, the filter is run again at the start of every retry.

There are two special conditions which, though available in users'
filter files, are designed for use in system filters. The condition
"first_delivery" is true only for the first attempt at delivering a
message, while "manually_thawed" is true only if the message has been
frozen, and subsequently thawed by an admin user. An explicit forced
delivery counts as a manual thaw, but thawing as a result of the
"auto_thaw" setting does not.

If the filter sets up any deliveries of its own, an extra header line
is added to them with the name "X-Envelope-to:". This contains up to
100 of the original message's envelope recipients.  If the filter
specifies any significant deliveries, the message's own recipient list
is ignored. Non-significant deliveries, however, are added to the
message's existing recipients.

Warning: If a system filter uses the "first_delivery" condition to
specify an `unseen' (non-significant) delivery, and that delivery does
not succeed, it will not be tried again.

The "message_filter" option names the filter file, while
"message_filter_user" and "message_filter_group" specify the uid and
gid to be used while processing it. If they are not set, the Exim uid
is used if available and if "seteuid()" is available; otherwise "root"
is used.

Important: If the system filter generates any deliveries directly to
files or pipes (via the "save" or "pipe" commands), transports to
handle these deliveries must be specified by setting
"message_filter_file_transport" and "message_filter_pipe_transport",
respectively. Similarly, "message_filter_reply_transport" must be set
to handle any autoreplies.

The filter file can contain any of the normal filtering commands, as
described in the separate document "Exim's interface to mail
filtering". However, remember that the system filter is run just once,
at the start of a delivery process, however many recipients the message
may have. For this reason, the variables $local_part and $domain are
not available, nor does the `personal' condition make any sense.

The filter variables $n0 - $n9 can be used in a system filter; when it
finishes, their values are copied into $sn0 - $sn9 and are thereby made
available to users' filter files. Thus a system filter can, for
example, set up a `score' for a message to which users' filter files
can refer.


File: exim.info,  Node: Additional commands for system filters,  Next: Per-address filtering,  Prev: The system message filter,  Up: System-wide message filtering

Additional commands for system filters
======================================

In a system filter, if a "deliver" command is followed by

     errors_to <some address>

in order to change the envelope sender (and hence the error reporting)
for that delivery, any address is permitted. (In a user filter, only
the current user's address can be set.)  For example, if some mail is
being monitored, you might use

     unseen deliver monitor@spying.example errors_to root@local.domain

to take a copy which would not be sent back to the normal error
reporting address if its delivery failed.

There are also some extra commands which are available only in system
filter files:

     fail
     freeze
     headers add <string>
     headers remove <string>

As well as the additional commands, there is also an extra expansion
variable, $recipients, containing a list of all the recipients of the
message, separated by commas and white space. The extra commands and
variable are not available in ordinary users' filter files. They are
faulted in normal use and in testing via -bf, but not if -bF is used.

The "freeze" and "fail" commands can optionally be followed by the word
"text" and a string containing an error message, for example:

     fail text "this message looks like spam to me"

The keyword "text" is optional if the next character is a double quote.
The "fail" command causes all recipients to be failed, while "freeze"
suspends all delivery attempts. It is ignored if the message has been
manually unfrozen and not manually frozen since. This means that
automatic freezing by a system filter can be used as a way of checking
out suspicious messages. If a message is found to be all right,
manually unfreezing it allows it to be delivered.

The interpretation of a system filter file ceases after a "freeze" or
"fail" command is obeyed. However, any deliveries that were set up
earlier in the filter file are honoured, so you can use a sequence such
as

     mail ...
     freeze

to send a specified message when the system filter is freezing (or
failing) something. The normal deliveries for the message do not, of
course, take place.

The argument for the "headers add" is a string which is expanded and
then added to the end of the message's headers. It is the
responsibility of the filter maintainer to make sure it conforms to RFC
822 syntax.  Leading white space is ignored, and if the string is
otherwise empty, or if the expansion is forced to fail, the command has
no effect. A newline is added at the end of the string if it lacks one.
More than one header may be added in one command by including `\n'
within the string.

The argument for "headers remove" is a colon-separated list of header
names.  This command applies only to those headers that are stored with
the message; ones such as "Envelope-To:" and "Return-Path:" that are
added at delivery time cannot be removed by this means.

Take great care with the "fail" command when basing the decision to
fail on the contents of the message, because this option causes a
normal delivery error message to be generated, and it will of course
include the contents of the original message and will therefore trigger
the "fail" command again (causing a mail loop) unless steps are taken
to prevent this. Testing the "error_message" condition is one way to
prevent this. You could use, for example

     if $message_body contains "this is spam" and not error_message
       then fail text "spam is not wanted here" endif

though of course that might still let through unwanted messages. The
alternative is clever checking of the body and/or headers to detect
error messages caused by the filter.


File: exim.info,  Node: Per-address filtering,  Prev: Additional commands for system filters,  Up: System-wide message filtering

Per-address filtering
=====================

In contrast to the system filter, which is run just once per message
for each delivery attempt, it is also possible to set up a system-wide
filtering operation that runs once for each address, for local
addresses only. In this case, variables such as $local_part and $domain
can be used, and indeed, the choice of filter file could be made
dependent on them. This is an example of a director which implements
such a filter:

     central_filter:
       driver = forwardfile
       file = /central/filters/$local_part
       no_check_local_user
       no_verify
       filter
       allow_system_actions

The setting of "allow_system_actions" permits the use of "freeze" and
"fail" in the filter file, but not the "headers" command (described
above) or the $recipients variable. As in the case of a system filter,
"freeze" and "fail" cause filter interpretation to cease, but any
deliveries that were previously set up are honoured.


File: exim.info,  Node: SMTP processing,  Next: Message processing,  Prev: System-wide message filtering,  Up: Top

SMTP processing
***************

Exim supports SMTP over TCP/IP, and also so-called `batched SMTP'. The
latter is the name for a process in which batches of messages are
stored in or read from files, in a format in which SMTP commands are
used to contain the envelope information. Such batches are delivered to
or received from other systems using some transport mechanism other
than Exim. For each of these kinds of SMTP processing there are two
aspects: outgoing and incoming. There is also support for a third kind
of SMTP when a message is passed from a local process to Exim by
running the SMTP protocol over the standard input and output. This is
called `local SMTP', and is an input process only.



* Menu:

* Outgoing SMTP over TCP/IP::
* Errors in outgoing SMTP::
* Variable Envelope Return Paths (VERP)::
* Incoming SMTP messages over TCP/IP::
* The VRFY and EXPN and DEBUG commands::
* The ETRN command::
* Incoming local SMTP::
* Outgoing batched SMTP::
* Incoming batched SMTP::


File: exim.info,  Node: Outgoing SMTP over TCP/IP,  Next: Errors in outgoing SMTP,  Prev: SMTP processing,  Up: SMTP processing

Outgoing SMTP over TCP/IP
=========================

Outgoing SMTP over TCP/IP is implemented by the "smtp" transport.  If,
in response to its EHLO command, it is told that the SIZE parameter is
supported, it adds SIZE=<n> to each subsequent MAIL command. The value
of <n> is the message size plus the value of the "size_addition" option
(default 1024) to allow for additions to the message such as
per-transport header lines, or changes made in a transport filter. If
"size_addition" is set negative, the use of SIZE is suppressed.

If the remote server advertises support for PIPELINING, Exim uses the
pipelining extension to SMTP (RFC 2197) to reduce the number of TCP/IP
packets required for the transaction.

If the remote server advertises support for the STARTTLS command, and
Exim was built to support TLS encryption, it tries to start a TLS
session unless the server matches "hosts_avoid_tls". See chapter
"Encrypted SMTP connections using TLS/SSL" for more details.

If the remote server advertises support for the AUTH command, and Exim
was built to support SMTP authentication, it scans the authenticators
configuration for any suitable client settings, as described in chapter
"SMTP authentication".

Responses from the remote host are supposed to be terminated by CR
followed by LF. However, there are known to be hosts that do not send
CR characters, so in order to be able to interwork with such hosts,
Exim treats LF on its own as a line terminator.

If a message contains a number of different addresses, all those with
the same characteristics (for example, the same envelope sender) that
resolve to the same set of hosts, in the same order, are sent in a
single SMTP transaction, even if they are for different domains, unless
there are more than the setting of the "max_rcpts" option in the "smtp"
transport allows, in which case they are split into groups containing
no more than "max_rcpts" addresses each. If "remote_max_parallel" is
greater than one, such groups may be sent in parallel sessions. The
order of hosts with identical MX values is not significant when
checking whether addresses can be batched in this way.

When the "smtp" transport suffers a temporary failure that is not
message-related, Exim updates its transport-specific database, which
contains records indexed by host name that remember which messages are
waiting for each particular host. It also updates the retry database
with new retry times.  Exim's retry hints are based on host name plus
IP address, so if one address of a multi-homed host is broken, it will
soon be skipped most of the time.  See the next section for more detail
about error handling.

When a message is successfully delivered over a TCP/IP SMTP connection,
Exim looks in the hints database for the transport to see if there are
any queued messages waiting for the host to which it is connected. If
it finds one, it creates a new Exim process using the -MC option (which
can only be used by a process running as root or the Exim user) and
passes the TCP/IP socket to it.  The new process does only those
deliveries that are routed to the connected host, and may in turn pass
the socket on to a third process, and so on.

If this is happening in a queue run, the queue-runner process must not
proceed to the next message in the queue until the whole sequence of
deliveries is complete. However, making each process wait for its
successor is not a good idea, as there may be many of them. To avoid
having to do this, a queue-runner process creates a pipe which is
passed to all the created processes, none of which actually write to
it. The queue-runner tries to read from the pipe. This causes it to
block until all the created processes have finished.

The "batch_max" option of the "smtp" transport can be used to limit the
number of messages sent down a single TCP/IP connection.  The second
and subsequent messages delivered down an existing connection are
identified in the main log by the addition of an asterisk after the
closing square bracket of the IP address.


File: exim.info,  Node: Errors in outgoing SMTP,  Next: Variable Envelope Return Paths (VERP),  Prev: Outgoing SMTP over TCP/IP,  Up: SMTP processing

Errors in outgoing SMTP
=======================

Three different kinds of error are recognized for outgoing SMTP: host
errors, message errors, and recipient errors.

  1. A host error is not associated with a particular message or with a
     particular recipient of a message. The host errors are:

        * Connection refused or timed out,

        * Any error response code on connection,

        * Any error response code to EHLO or HELO,

        * Loss of connection at any time, except after `.',

        * I/O errors at any time,

        * Timeouts during the session, other than in response to MAIL,
          RCPT or the `.' at the end of the data.

     A permanent error response on connection, or in response to EHLO,
     causes all addresses routed to the host to be failed. Any other
     host error causes all addresses to be deferred, and retry data to
     be created for the host.  It is not tried again, for any message,
     until its retry time arrives. If the current set of addresses are
     not all delivered in this run (to some alternative host), the
     message is added to the list of those waiting for this host, so if
     it is still undelivered when a subsequent successful delivery is
     made to the host, it will be sent down the same SMTP connection.

  2. A message error is associated with a particular message when sent
     to a particular host, but not with a particular recipient of the
     message. The message errors are:

        * Any error response code to MAIL, DATA, or the `.' that
          terminates the data,

        * Timeout after MAIL,

        * Timeout or loss of connection after the `.' that terminates
          the data. A timeout after the DATA command itself is treated
          as a host error, as is loss of connection at any other time.

     A permanent error response (5xx) causes all addresses to be
     failed, and a delivery error report to be returned to the sender.
     A temporary error response (4xx) or one of the timeouts causes all
     addresses to be deferred. Retry data is not created for the host,
     but instead, a retry record for the combination of host plus
     message id is created. The message is not added to the list of
     those waiting for this host. This ensures that the failing message
     will not be sent to this host again until the retry time arrives.
     However, other messages that are routed to the host are not
     affected, so if it is some property of the message that is causing
     the error, it will not stop the delivery of other mail.

     If the remote host specified support for the SIZE parameter in its
     response to EHLO, Exim adds SIZE=nnn to the MAIL command, so an
     over-large message will cause a message error because it will
     arrive as a response to MAIL.

  3. A recipient error is associated with a particular recipient of a
     message. The recipient errors are:

        * Any error response to RCPT,

        * Timeout after RCPT.

     A permanent error response (5xx) causes the recipient address to be
     failed, and a delivery error report to be returned to the sender.
     A temporary error response (4xx) or a timeout causes the failing
     address to be deferred, and routing retry data to be created for
     it. This is used to delay processing of the address in subsequent
     queue runs, until its routing retry time arrives. This applies to
     all messages, but because it operates only in queue runs, one
     attempt will be made to deliver a new message to the failing
     address before the delay starts to operate. This ensures that, if
     the failure is really related to the message rather than the
     recipient (`message too big for this recipient' is a possible
     example), other messages have a chance of getting delivered.
     However, if a delivery to the address does succeed, the retry
     information gets cleared, so all stuck messages get tried again,
     and the retry clock is reset.

     The message is not added to the list of those waiting for this
     host. Use of the host for other messages is unaffected, and except
     in the case of a timeout, other recipients are processed
     independently, and may be successfully delivered in the current
     SMTP session. After a timeout it is of course impossible to
     proceed with the session, so all addresses get deferred. However,
     those other than the one that failed do not suffer any subsequent
     retry delays. Therefore, if one recipient is causing trouble, the
     others have a chance of getting through when a subsequent delivery
     attempt occurs before the failing recipient's retry time.

In all cases, if there are other hosts (or IP addresses) available for
the current set of addresses (for example, from multiple MX records),
they are tried in this run for any undelivered addresses, subject of
course to their own retry data. In other words, recipient error retry
data does not take effect until the next delivery attempt.

Some hosts have been observed to give temporary error responses to every
MAIL command at certain times (`insufficient space' has been seen). It
would be nice if such circumstances could be recognized, and defer data
for the host itself created, but this is not possible within the
current Exim design.  What actually happens is that retry data for
every (host, message) combination is created.

The reason that timeouts after MAIL and RCPT are treated specially is
that these can sometimes arise as a result of the remote host's
verification procedures. Exim makes this assumption, and treats them as
if a temporary error response had been received. A timeout after `.' is
treated specially because it is known that some broken implementations
fail to recognize the end of the message if the last character of the
last line is a binary zero. Thus is it helpful to treat this case as a
message error.

Timeouts at other times are treated as host errors, assuming a problem
with the host, or the connection to it. If a timeout after MAIL, RCPT,
or `.' is really a connection problem, the assumption is that at the
next try the timeout is likely to occur at some other point in the
dialogue, causing it then to be treated as a host error.

There is experimental evidence that some MTAs drop the connection after
the terminating `.' if they don't like the contents of the message for
some reason, in contravention of the RFC, which indicates that a 5xx
response should be given. That is why Exim treats this case as a
message rather than a host error, in order not to delay other messages
to the same host.


File: exim.info,  Node: Variable Envelope Return Paths (VERP),  Next: Incoming SMTP messages over TCP/IP,  Prev: Errors in outgoing SMTP,  Up: SMTP processing

Variable Envelope Return Paths (VERP)
=====================================

Variable Envelope Return Paths - see
"ftp://koobera.math.uic.edu/www/proto/verp.txt" - can be supported in
Exim by using the "return_path" generic transport option to rewrite the
return path at transport time. For example, the following could be used
on an smtp transport:

     return_path = \
       ${if match {$return_path}{^(.+?)-request@your.domain\$}\
       {$1-request=$local_part%$domain@your.domain}fail}

This has the effect of rewriting the return path (envelope sender) on
all outgoing SMTP messages, if the local part of the original return
path ends in `-request', and the domain is "your.domain". The rewriting
inserts the local part and domain of the recipient into the return
path. If, for example, a message with return path
"somelist-request@your.domain" is sent to "subscriber@other.domain",
the return path is rewritten as

     somelist-request=subscriber%other.domain@your.domain

For this to work, you must arrange for outgoing messages that have
`-request' in their return paths to have just a single recipient. This
can be done by setting

     max_rcpt = 1

in the smtp transport. Otherwise a single copy of a message might be
addressed to several different recipients in the same domain, in which
case $local_part is not available (because it is not unique). Of
course, if you do start sending out messages with this kind of return
path, you must also configure Exim to accept the bounce messages that
come back to those paths.  Typically this would be done by setting a
"suffix" option in a suitable director.

The overhead incurred in using VERP depends very much on the size of the
message, the number of recipient addresses that resolve to the same
remote host, and the speed of the connection over which the message is
being sent. If a lot of addresses resolve to the same host and the
connection is slow, sending a separate copy of the message for each
address may take substantially longer than sending a single copy with
many recipients (for which VERP cannot be used).


File: exim.info,  Node: Incoming SMTP messages over TCP/IP,  Next: The VRFY and EXPN and DEBUG commands,  Prev: Variable Envelope Return Paths (VERP),  Up: SMTP processing

Incoming SMTP messages over TCP/IP
==================================

Incoming SMTP messages can be accepted in one of two ways: by running a
listening daemon, or by using "inetd". In the latter case, the entry in
"/etc/inetd.conf" should be like this:

     smtp  stream  tcp  nowait  exim  /opt/exim/bin/exim  in.exim  -bs

Exim distinguishes between this case and the case of a user agent using
the -bs option by checking whether the standard input is a socket using
the "getpeername()" function.

By default, Exim does not make a log entry when a remote hosts connects
or disconnects (either via the daemon or "inetd"), unless the
disconnection is unexpected. It can be made to write such log entries
by setting the "log_smtp_connections" option.

Commands from the remote host are supposed to be terminated by CR
followed by LF. However, there are known to be hosts that do not send
CR characters, so in order to be able to interwork with such hosts,
Exim treats LF on its own as a line terminator.

One area that sometimes gives rise to problems concerns the EHLO or
HELO commands. Some clients send syntactically invalid versions of these
commands, which Exim rejects by default. (This is nothing to do with
verifying the data that is sent, so "helo_verify" is not relevant.) You
can tell Exim not to apply a syntax check by setting
"helo_accept_junk_hosts" to match the broken hosts that send invalid
commands.

The amount of disc space available is checked whenever SIZE is received
on a MAIL command, independently of whether "message_size_limit" or
"check_spool_space" is configured, unless "smtp_check_spool_space" is
set false. A temporary error is given if there isn't enough. If
"check_spool_space" is set, the check is for that amount of space plus
the value given with SIZE, that is, it checks that the addition of the
incoming message will not reduce the space below the threshold.

When a message is successfully received, Exim includes the local
message id in its response to the final `.' that terminates the data.
If the remote host logs this text it can help with tracing what has
happened to a message.

The Exim daemon can limit the number of simultaneous incoming
connections it is prepared to handle (see the "smtp_accept_max"
option). It can also limit the number of simultaneous incoming
connections from a single remote host (see the
"smtp_accept_max_per_host" option). Additional connection attempts are
rejected using the SMTP temporary error code 421.

On some operating systems the SIGCHLD signal that is used to detect
when a subprocess has finished can get lost at busy times. However, the
daemon looks for completed subprocesses every time it wakes up, so
provided there are other things happening (new incoming calls, starts
of queue runs), the completion of processes created to handle incoming
calls should get noticed eventually. If, however, Exim appears not to
be accepting as many incoming connections as expected, sending the
daemon a SIGCHLD signal will wake it up and cause it to check for any
completed subprocesses.

When running as a daemon, Exim can reserve some SMTP slots for specific
hosts, and can also be set up to reject SMTP calls from non-reserved
hosts at times of high system load - for details see the
"smtp_accept_reserve", "smtp_load_reserve", and "smtp_reserve_hosts"
options. The load check applies in both the daemon and "inetd" cases.

Exim normally starts a delivery process for each message received,
though this can be varied by means of the -odq command line option and
the "queue_only", "queue_only_file", and "queue_only_load" options. The
number of simultaneously running delivery processes started in this way
from SMTP input can be limited by the "smtp_accept_queue" and
"smtp_accept_queue_per_connection" options. When either limit is
reached, subsequently received messages are just put on the input queue.

The controls that involve counts of incoming SMTP calls
("smtp_accept_max" "smtp_accept_queue", "smtp_accept_reserve") are not
available when Exim is started up from the "inetd" daemon, since each
connection is handled by an entirely independent Exim process. Control
by load average is, however, available with "inetd".

Exim can be configured to verify addresses in incoming SMTP commands as
they are received. See chapter "Verification of incoming mail" for
details. It can also be configured to rewrite addresses at this time -
before any syntax checking is done. See section "The SMTP-time
rewriting flag" in chapter "Address rewriting".


File: exim.info,  Node: The VRFY and EXPN and DEBUG commands,  Next: The ETRN command,  Prev: Incoming SMTP messages over TCP/IP,  Up: SMTP processing

The VRFY, EXPN, and DEBUG commands
==================================

The SMTP command VRFY is accepted only when the configuration option
"smtp_verify" is set, and if so, it runs exactly the same code as when
Exim is called with the -bv option.  The SMTP command EXPN is is
permitted only if the calling host matches "smtp_expn_hosts" (add
`localhost' if you want calls to 127.0.0.1 to be able to use it). A
single-level expansion of the address is done. EXPN is treated as an
`address test' (similar to the -bt option) rather than a verification
(the -bv option). If an unqualified local part is given as the argument
to EXPN, it is qualified with "qualify_domain".  Rejections of VRFY and
EXPN commands are logged on the main and reject logs, and VRFY
verification failures are logged on the main log for consistency with
RCPT failures.

The SMTP command DEBUG is not supported at all. Occurrences of this
command are rejected, and the incident is logged.


File: exim.info,  Node: The ETRN command,  Next: Incoming local SMTP,  Prev: The VRFY and EXPN and DEBUG commands,  Up: SMTP processing

The ETRN command
================

RFC 1985 describes an SMTP command called ETRN that is designed to
overcome the security problems of the TURN command (which has fallen
into disuse). Exim recognizes ETRN if the calling host matches
"smtp_etrn_hosts".  Attempts to use ETRN from other hosts are logged on
the main and reject logs; when ETRN is accepted, it is logged on the
main log.

The ETRN command is concerned with `releasing' messages that are
awaiting delivery to certain hosts. As Exim does not organize its
message queue by host, the only form of ETRN that is supported by
default is the one where the text starts with the `#' prefix, in which
case the remainder of the text is specific to the SMTP server. A valid
ETRN command causes a run of Exim with the -R option to happen, with
the remainder of the ETRN text as its argument. For example,

     ETRN #brigadoon

runs the command

     exim -R brigadoon

which causes a delivery attempt on all messages with undelivered
addresses containing the text `brigadoon'. Because a separate delivery
process is run to do the delivery, there is no security risk with ETRN.

When "smtp_etrn_serialize" is set (the default), it prevents the
simultaneous execution of more than one queue run for the same argument
string as a result of an ETRN command. This prevents a mis-behaving
client from starting more than one queue-runner at once. Exim
implements the serialization by means of a hints database in which a
record is written whenever a process is started by ETRN, and deleted
when a -R queue run completes.

Obviously there is scope for hints records to get left lying around if
there is a system or program crash. To guard against this, Exim ignores
any records that are more than six hours old, but you should normally
arrange to delete any files in the "spool/db" directory whose names
begin with `serialize-' after a reboot.

For more control over what ETRN does, the "smtp_etrn_command" option can
used. This specifies a command that is run whenever ETRN is received,
whatever the form of its argument. For example:

     smtp_etrn_command = /etc/etrn_command $domain $sender_host_address

The string is split up into arguments which are independently expanded.
The expansion variable $domain is set to the argument of the ETRN
command, and no syntax checking is done on the contents of this
argument. A new freestanding process is created to run the command.
Exim does not wait for it to complete, so its status code is not
checked. As Exim is normally running under its own uid and gid when
receiving incoming SMTP, it is not possible for it to change them
before running the command.

If you use "smtp_etrn_command" to do something other than run Exim with
the -R option, you must disable "smtp_etrn_serialize", because
otherwise hints never get deleted, and further ETRN commands are
ignored until the hints time out.


File: exim.info,  Node: Incoming local SMTP,  Next: Outgoing batched SMTP,  Prev: The ETRN command,  Up: SMTP processing

Incoming local SMTP
===================

Some user agents use SMTP to pass messages to their local MTA using the
standard input and output, as opposed to passing the envelope on the
command line and writing the message to the standard input. This is
supported by the -bs option. This form of SMTP is handled in the same
way as incoming messages over TCP/IP, except that all host-specific
processing is bypassed, and any envelope sender given in a MAIL command
is ignored unless the caller is trusted.


File: exim.info,  Node: Outgoing batched SMTP,  Next: Incoming batched SMTP,  Prev: Incoming local SMTP,  Up: SMTP processing

Outgoing batched SMTP
=====================

Both the "appendfile" and "pipe" transports can be used for handling
batched SMTP. Each has an option called "bsmtp" which, if set to
anything other than `none' causes the message to be output in SMTP
format. The message is written to the file or pipe preceded by the SMTP
commands MAIL and RCPT, and followed by a line containing a single dot.
The SMTP command HELO is not normally used, but if the transport's
"bsmtp_helo" option is set true, a HELO command line precedes each
message. No SMTP responses are possible for this form of delivery.  All
it is doing is using SMTP commands as a way of transmitting the envelope
along with the message.

Lines in the message that start with a dot have an extra dot added. If
the "prefix" option is set, its contents are included after the SMTP
commands, and the contents of "suffix" appear at the end of the
message, before the terminating dot; normally these options are
specified as empty, to override the defaults.

The value of the "bsmtp" option determines how multiple addresses in a
single message may be batched, if other conditions permit. If the value
of "bsmtp" is `one', there is no batching, and a copy of the message is
output for each address. If the value is `domain' then a single copy
(with multiple RCPT commands) is output for all addresses that have the
same domain. If the value is `all' then only a single copy of the
message is written. The batching is further constrained by other
parameters:

   * If any of the transport's expandable strings contain a reference
     to $local_part, no batching takes place.

   * If any of the transport's expandable strings contains a reference
     to $domain, only domain batching is done.

   * Addresses are not batched if they have different error addresses,
     associated hosts, header additions or removals and so on.

   * The uid and gid for delivery must be explicitly set. This is
     normally done in the transport, but if they are specified by a
     router or director, batching occurs only for addresses that have
     the same uid/gid set up.

When one or more messages are routed to a BSMTP transport by a router
that sets up a host list, the name of the first host on the list is
available to the transport in the variable $host.  Here is an example
of such a transport and router for batched SMTP:

     # transport
     smtp_appendfile:
       driver = appendfile
       directory = /var/bsmtp/$host
       bsmtp = all
       prefix =
       suffix =
       user = exim
     
     # router
     route_append:
       driver = domainlist
       transport = smtp_appendfile
       route_list = some.domain  batch.host

This causes messages addressed to "some.domain" to be written in
batched SMTP format to "/var/bsmtp/batch.host", with only a single copy
of each message.  Note that prefix and suffix must be explicitly
changed from their defaults.


File: exim.info,  Node: Incoming batched SMTP,  Prev: Outgoing batched SMTP,  Up: SMTP processing

Incoming batched SMTP
=====================

The -bS command line option causes Exim to accept one or more messages
by reading SMTP on the standard input, but to generate no responses. If
the caller is trusted, the senders in the MAIL commands are believed;
otherwise the sender is always the caller of Exim. Unqualified senders
and receivers are not rejected (there seems little point) but instead
just get qualified. If "sender_verify" is set, sender verification
takes place only if "sender_verify_batch" is set (it defaults unset).
Receiver verification and administrative rejection is not done, even if
configured. HELO and EHLO act as RSET; VRFY, EXPN, ETRN, HELP, and
DEBUG act as NOOP; QUIT quits.

If any error is detected while reading a message, including a missing
`.' at the end, Exim gives up immediately. It writes details of the
error to the standard output in a stylized way that the calling program
should be able to make some use of automatically, for example:

     554 Unexpected end of file
     Transaction started in line 10
     Error detected in line 14

It writes a more verbose version, for human consumption, to the
standard error file, for example:

     An error was detected while processing a file of BSMTP input.
     The error message was:
     
       501 '>' missing at end of address
     
     The SMTP transaction started in line 10.
     The error was detected in line 12.
     The SMTP command at fault was:
     
        rcpt to:<malformed@in.com.plete
     
     1 previous message was successfully processed.
     The rest of the batch was abandoned.

The return code from Exim is zero only if there were no errors. It is 1
if some messages were accepted before an error was detected, and 2 if
no messages were accepted.


File: exim.info,  Node: Message processing,  Next: Automatic mail processing,  Prev: SMTP processing,  Up: Top

Message processing
******************

Exim performs various transformations on the sender and recipient
addresses of all messages that it handles, and also on the messages'
header lines. Some of these are optional and configurable, while others
always take place. All of this processing, except rewriting as a result
of routing, happens when a message is received, before it is first
written to the spool.

RFC 822 makes provision for headers starting with the string `Resent-'.
It states that in general, the `Resent-' fields should be treated as
containing a set of information that is independent of the set of
original fields, and that information for one set should not
automatically be taken from the other. If Exim finds any `Resent-'
headers in the message, it applies the header transformations described
below only to the `Resent-' header set, leaving the unqualified set
alone.



* Menu:

* Unqualified addresses::
* The UUCP From line::
* The Bcc header::
* The Date header::
* The Delivery-date header::
* The Envelope-to header::
* The From header::
* The Message-id header::
* The Received header::
* The Return-path header::
* The Sender header::
* The To header::
* Adding and removing headers::
* Constructed addresses::
* Case of local parts::
* Dots in local parts::
* Rewriting addresses::


File: exim.info,  Node: Unqualified addresses,  Next: The UUCP From line,  Prev: Message processing,  Up: Message processing

Unqualified addresses
=====================

By default, Exim expects every address it receives from an external
host to be fully qualified. Unqualified addresses cause negative
responses to SMTP commands. However, because SMTP is used as a means of
transporting messages from MUAs running on personal workstations, there
is sometimes a requirement to accept unqualified addresses from
specific hosts or IP networks.

Exim has two options that separately control which hosts may send
unqualified sender or receiver addresses in SMTP commands, namely
"sender_unqualified_hosts" and "receiver_unqualified_hosts". In both
cases, if an unqualified address is accepted, it is qualified by adding
the value of "qualify_domain" or "qualify_recipient", as appropriate.

Unqualified addresses are accepted only from local sources or from
hosts that match one of the "receiver_unqualified" or
"sender_unqualified" options, as appropriate.


File: exim.info,  Node: The UUCP From line,  Next: The Bcc header,  Prev: Unqualified addresses,  Up: Message processing

The UUCP From line
==================

Messages that have come from UUCP (and some other applications) often
begin with a line containing the envelope sender and a timestamp,
following the word `From'. Examples of two common formats are:

     From a.oakley@berlin.mus Fri Jan  5 12:35 GMT 1996
     From f.butler@berlin.mus Fri, 7 Jan 97 14:00:00 GMT

This line precedes the RFC 822 header lines. For compatibility with
Sendmail, Exim recognizes such lines at the start of messages that are
submitted to it via the command line (that is, on the standard input).
It does not recognize such lines in incoming SMTP messages, unless the
sending host matches "ignore_fromline_hosts" or the -bs option was used
for a local message and "ignore_fromline_local" is set. The recognition
is controlled by a regular expression that is defined by the
"uucp_from_pattern" option, whose default value matches the two common
cases shown above and puts the address that follows `From' into $1.

When the caller of Exim for a non-SMTP message is a trusted user, the
message's sender address is constructed by expanding the contents of
"uucp_sender_address", whose default value is `$1'. This is then parsed
as an RFC 822 address. If there is no domain, the local part is
qualified with "qualify_domain" unless it is the empty string. However,
if the command line -f option is used, it overrides the `From' line.

If the caller of Exim is not trusted, the `From' line is recognized,
but the sender address is not changed. This is also the case for
incoming SMTP messages that are permitted to contain `From' lines.

Only one `From' line is recognized. If there is more than one, the
second is treated as a data line that starts the body of the message,
as it is not valid as a header line. This also happens if a `From' line
is present in an incoming SMTP message from a source that is not
permitted to send them.


File: exim.info,  Node: The Bcc header,  Next: The Date header,  Prev: The UUCP From line,  Up: Message processing

The Bcc header
==============

If Exim is called with the -t option, to take recipient addresses from a
message's headers, it removes any "Bcc:" header that may exist (after
extracting its addresses), unless the message has no "To:" or "Cc:"
header, in which case a "Bcc:" header with no addresses is left in the
message, in accordance with RFC 822. If -t is not present on the
command line, any existing "Bcc:" header is not removed.

If Exim is called to receive a message with the recipient addresses
given on the command line, and there is no "Bcc:", "To:", or "Cc:"
header in the message, it normally adds a "To:" header, listing the
recipients. Some mailing list software is known to submit messages in
this way, and in this case the creation of a "To:" header is not what
is wanted. If the "always_bcc" option is set, Exim adds an empty "Bcc:"
header instead in this circumstance.


File: exim.info,  Node: The Date header,  Next: The Delivery-date header,  Prev: The Bcc header,  Up: Message processing

The Date header
===============

If a message has no "Date:" header, Exim adds one, giving the current
date and time.


File: exim.info,  Node: The Delivery-date header,  Next: The Envelope-to header,  Prev: The Date header,  Up: Message processing

The Delivery-date header
========================

"Delivery-date:" headers are not part of the standard RFC 822 header
set. Exim can be configured to add them to the final delivery of
messages. (See the generic "delivery_date_add" transport option.) They
should not be present in messages in transit. If the
"delivery_date_remove" configuration option is set (the default), Exim
removes "Delivery-date:" headers from incoming messages.


File: exim.info,  Node: The Envelope-to header,  Next: The From header,  Prev: The Delivery-date header,  Up: Message processing

The Envelope-to header
======================

"Envelope-to:" headers are not part of the standard RFC 822 header set.
Exim can be configured to add them to the final delivery of messages.
(See the generic "envelope_to_add" transport option.) They should not
be present in messages in transit. If the "envelope_to_remove"
configuration option is set (the default), Exim removes "Envelope-to:"
headers from incoming messages.


File: exim.info,  Node: The From header,  Next: The Message-id header,  Prev: The Envelope-to header,  Up: Message processing

The From header
===============

If an incoming message does not contain a "From:" header, Exim adds one
containing the sender's address. This is obtained from the message's
envelope in the case of remote messages; for locally-generated messages
the calling user's login name and full name are used to construct an
address, as described in section "Constructed addresses". They are
obtained from the password file entry by calling "getpwuid()" (but see
the "unknown_login" configuration option). The address is qualified
with "qualify_domain".

For compatibility with Sendmail, if an incoming, non-SMTP message has a
"From:" header containing just the unqualified login name of the
calling user, this is replaced by an address containing the user's
login name and full name as described in section "Constructed
addresses".


File: exim.info,  Node: The Message-id header,  Next: The Received header,  Prev: The From header,  Up: Message processing

The Message-id header
=====================

If an incoming message does not contain a "Message-id:" header, Exim
constructs one and adds it to the message. The id is constructed from
Exim's internal message id, preceded by the letter E to ensure it
starts with a letter, and followed by @ and the primary host name.
Additional information can be included in this header by setting the
"message_id_header_text" option.


File: exim.info,  Node: The Received header,  Next: The Return-path header,  Prev: The Message-id header,  Up: Message processing

The Received header
===================

A "Received:" header is added at the start of every message. The
contents of this header are defined by the "received_header_text"
configuration option, and Exim automatically adds a semicolon and a
timestamp to the configured string.


File: exim.info,  Node: The Return-path header,  Next: The Sender header,  Prev: The Received header,  Up: Message processing

The Return-path header
======================

"Return-path:" headers are defined as something the MTA may insert when
it does the final delivery of messages. (See the generic
"return_path_add" transport option.) Therefore, they should not be
present in messages in transit. If the "return_path_remove"
configuration option is set (the default), Exim removes "Return-path:"
headers from incoming messages.


File: exim.info,  Node: The Sender header,  Next: The To header,  Prev: The Return-path header,  Up: Message processing

The Sender header
=================

For locally-originated messages, unless originated by a trusted user,
any existing "Sender:" header is removed. For non-trusted callers,
unless "local_from_check" is set false, a check is made to see if the
address given in the "From:" header is the correct (local) sender of
the message (prefixes and suffixes for the local part can be permitted
via "local_from_prefix" and "local_from_suffix"). If not, a "Sender:"
header giving the true sender address is added to the message. No
processing of the "Sender:" header is done for messages originating
externally.


File: exim.info,  Node: The To header,  Next: Adding and removing headers,  Prev: The Sender header,  Up: Message processing

The To header
=============

If a message has no "To:", "Cc:", or "Bcc:" header, Exim adds an empty
"Bcc:" header, in accordance with RFC 822, except when the message is
being received locally with the recipients supplied on the command
line. In this case, a "To:" header listing the recipients is normally
added. Some mailing list software is known to submit messages in this
way, and in this case the creation of a "To:" header is not what is
wanted. If the "always_bcc" option is set, Exim adds an empty "Bcc:"
header instead in this circumstance. An "Apparently-to:" header is
never added.


File: exim.info,  Node: Adding and removing headers,  Next: Constructed addresses,  Prev: The To header,  Up: Message processing

Adding and removing headers
===========================

The addition and removal of headers can be specified on any of the
drivers, and also in system filter files. Changes specified in the
system filter affect all deliveries of a message.

Header changes specified on a director or router affect all addresses
handled by that driver, and also any new addresses it generates. If an
address passes through several directors and/or routers, the changes
are cumulative. When a message is processed by a transport, the
message's original set of headers is output, except for those named in
any "headers_remove" options that the address has encountered as it was
processed, and any in the transport's own "headers_remove" option. Then
any new headers from any "headers_add" options are output.


File: exim.info,  Node: Constructed addresses,  Next: Case of local parts,  Prev: Adding and removing headers,  Up: Message processing

Constructed addresses
=====================

When Exim constructs a sender address for a locally-generated message,
it uses the form

     <user name> <<login>@<qualify_domain>>

For example:

     Zaphod Beeblebrox <zaphod@end.univ>

The user name is obtained from the -F command line option if set, or
otherwise by looking up the calling user by "getpwuid()" and extracting
the `gecos' field from the password entry. If the `gecos' field
contains an ampersand character, this is replaced by the login name
with the first letter upper-cased, as is conventional in a number of
operating systems. See the "gecos_name" option for a way to tailor the
handling of the `gecos' field. The "unknown_username" option can be
used to specify user names in cases when there is no password file
entry.

In all cases, the user name is made to conform to RFC 822 by quoting
all or parts of it if necessary. In addition, if it contains any
non-printing characters, it is encoded as described in RFC 2047, which
defines a way of including non-ASCII characters in header lines. The
setting of "print_topbitchars" controls whether characters with the top
bit set (that is, with codes greater than 127) count as printing
characters or not.


File: exim.info,  Node: Case of local parts,  Next: Dots in local parts,  Prev: Constructed addresses,  Up: Message processing

Case of local parts
===================

RFC 822 states that the case of letters in the local parts of addresses
cannot be assumed not to be significant. Exim preserves the case of
local parts of remote addresses. However, when it is processing an
address in one of its local domains, the case of letters in the local
part is significant only when "locally_caseless" is unset. This option
is set by default, and this causes Exim to lowercase local parts in
local domains before processing them.

If you must have mixed-case user names in your password file, the best
way to proceed, assuming you want case-independent handling of incoming
email, is to unset "locally_caseless" and then set up an initial
"smartuser" director to convert incoming local parts to the correct
case by a file lookup such as

     new_address = ${lookup{${lc:$local_part}}cdb\
                   {/etc/usercased.cdb}{$value}fail}\
                   @$domain


File: exim.info,  Node: Dots in local parts,  Next: Rewriting addresses,  Prev: Case of local parts,  Up: Message processing

Dots in local parts
===================

RFC 822 forbids empty components in local parts. That is, an unquoted
local part may not begin or end with a dot, nor have two consecutive
dots in the middle. However, it seems that many MTAs do not enforce
this, so Exim permits empty components for compatibility.


File: exim.info,  Node: Rewriting addresses,  Prev: Dots in local parts,  Up: Message processing

Rewriting addresses
===================

Rewriting of sender and recipient addresses, and addresses in headers,
can happen automatically, or as the result of configuration options, as
described in chapter "Address rewriting".  The headers that may be
affected by this are "Bcc:", "Cc:", "From:", "Reply-To:", "Sender:",
and "To:".

Automatic rewriting includes qualification, as mentioned above. The
other case in which it can happen is when an incomplete non-local
domain is given. The routing process may cause this to be expanded into
the full domain name. For example, a header such as

     To: hare@teaparty

might get rewritten as

     To: hare@teaparty.wonderland.fict.book

Rewriting as a result of routing is the one kind of message processing
that does not happen at input time, as it cannot be done until the
address has been routed.

Strictly, one should not do any deliveries of a message until all its
addresses have been routed, in case any of the headers get changed as a
result of routing. However, doing this in practice would hold up many
deliveries for unreasonable amounts of time, just because one address
could not immediately be routed. Exim therefore does not delay other
deliveries when routing of one or more addresses is deferred.


File: exim.info,  Node: Automatic mail processing,  Next: Log files,  Prev: Message processing,  Up: Top

Automatic mail processing
*************************

This chapter describes some of the ways in which incoming mail can be
processed automatically, either on a system-wide basis, or as specified
by individual users.



* Menu:

* System-wide automatic processing::
* Taking copies of mail::
* Automatic processing by users::
* Simplified vacation processing::


File: exim.info,  Node: System-wide automatic processing,  Next: Taking copies of mail,  Prev: Automatic mail processing,  Up: Automatic mail processing

System-wide automatic processing
================================

Simple re-addressing of messages can be handled by "aliasfile" or
"forwardfile" directors. The particular case of mailing lists is
covered in chapter "Using Exim to handle mailing lists". Other kinds of
automatic processing can be handled by suitable configurations of
directors and transports. As an example, here is an extract from the
configuration of a system which tries to send back helpful information
when a message is received for an unknown user. The last director in
the configuration is:

     unknownuser:
       driver = smartuser
       transport = unknownuser_pipe
       no_verify

This collects all the addresses whose local parts haven't been matched
by any other director, and directs them to a special pipe transport,
whose configuration is:

     unknownuser_pipe:
       driver = pipe
       command = /opt/exim/util/baduser.sh
       ignore_status
       return_output
       user = nobody

The script is run as the user `nobody', and it can apply heuristics
such as soundex search to the local part, in an attempt to produce a
list of possible users for whom the message might have been intended.
This is then included in a message that is written to its standard
output; Exim picks this up and returns it to the sender as part of the
delivery error message.

Chapter "System-wide message filtering" describes how to arrange to run
a system filter file once per message. Sometimes there is a requirement
to set up similar automatic processing, but on a per-address basis,
that is, the filter is run once for each address. This can be done by
using a director such as the following:

     filter_per_address:
       driver = forwardfile
       no_verify
       filter
       file = /etc/per-address-filter
       no_check_local_user
       user = nobody

See the separate document entitled "Exim's interface to mail filtering"
which describes the available filtering commands. Care should be taken
to ensure that none of the commands in the filter file specify a
significant delivery if the message is to go on to be delivered to its
intended recipient. The director will not then claim to have dealt with
the address, so it will be passed on to subsequent directors to be
delivered in the normal way. Note that a traditional (non-filter)
`.forward' file does not have this property, so cannot be used in this
way, though you could use it to forward all mail for a particular
domain to a single recipient in a different domain.


File: exim.info,  Node: Taking copies of mail,  Next: Automatic processing by users,  Prev: System-wide automatic processing,  Up: Automatic mail processing

Taking copies of mail
=====================

Some installations have policies that require archive copies of all
messages to be made. A single copy of each message can easily be taken
by an appropriate command in a system filter, which could, for example,
use a different file for each day's messages.

There is also a shadow transport mechanism that can be used to take
copies of messages that are successfully delivered by local transports,
one copy per delivery. This could be used, inter alia, to implement
automatic notification of delivery by sites that insist on doing such
things.


File: exim.info,  Node: Automatic processing by users,  Next: Simplified vacation processing,  Prev: Taking copies of mail,  Up: Automatic mail processing

Automatic processing by users
=============================

Users can cause their mail to be processed automatically by creating
`.forward' files, provided that Exim's configuration contains an
appropriate "forwardfile" director. Traditionally, such files contain
just a list of forwarding addresses, local files, and pipe commands,
but if the "forwardfile" director has the "filter" option set, users
can access Exim's filtering facilities by beginning a `.forward' file
with the text `# Exim filter'. Details of the syntax and semantics of
filter files are described in a separate document entitled "Exim's
interface to mail filtering"; this is intended for use by end users.

The name `.forward' is purely conventional; a "forwardfile" director
can be configured to use any arbitrary name. As there are some finger
daemons that display the contents of users' `.forward' files, some
sites might like to use a different name when mail filtering is
provided.

What users may do in their `.forward' files can be constrained by
various options of the "forwardfile" director:

   * If the "filter" option is not set, only traditional `.forward'
     files are permitted.

   * If the "forbid_file" option is set, neither a traditional
     `.forward' file, nor a filter file may direct that a message be
     appended to a particular local file. An attempt to do so causes a
     delivery error.

   * If the "forbid_filter_log" option is set, the use of the "log"
     command in a filter file is not permitted.

   * If the "forbid_pipe" option is set, neither a traditional
     `.forward' file, nor a filter file may direct that a message be
     piped to a user-specified command. An attempt to do so causes a
     delivery error.

   * If the "forbid_reply" option is set, a filter file may not direct
     that a new mail message be created. An attempt to do so causes a
     delivery error.

If piping is permitted, the pipe transport that is used (conventionally
called "address_pipe") can constrain the command to be taken from a
particular set of files. Pipe commands generated from traditional
`.forward' files are not string-expanded, but when a pipe command is
generated in a filter file, each argument is separately expanded.

If delivery to specified files is permitted, the "appendfile" transport
that is used (conventionally called "address_file") can specify that
the file must already exist, or can restrict the whereabouts of its
creation by means of the "create_file" option.


File: exim.info,  Node: Simplified vacation processing,  Prev: Automatic processing by users,  Up: Automatic mail processing

Simplified vacation processing
==============================

The traditional way of running the "vacation" program is for a user to
set up a pipe command in a `.forward' file. This is prone to error by
inexperienced users. There are two features of Exim that can be used to
make this process simpler for users:

   * A local part prefix such as `vacation-' can be specified on a
     director which causes the message to be delivered directly to the
     "vacation" program, or uses Exim's "autoreply" transport. The
     contents of a user's `.forward' file are then much simpler. For
     example:

          spqr, vacation-spqr

   * The "require_files" generic director option can be used to trigger
     a vacation delivery by checking for the existence of a certain
     file in the user's home directory. The "unseen" generic option
     should also be used, to ensure that the original delivery also
     proceeds. In this case, all the user has to do is to create a file
     called, say, ".vacation", containing a vacation message.

Another advantage of both these methods is that they both work even
when the use of arbitrary pipes by users is locked out.


File: exim.info,  Node: Log files,  Next: Day-to-day management,  Prev: Automatic mail processing,  Up: Top

Log files
*********

Exim writes three different logs, referred to as the main log, the
reject log, and the panic log.

   * The main log records the arrival of each message and each delivery
     in a single logical line in each case. The format is as compact as
     possible, in an attempt to keep down the size of log files.
     Two-character flag sequences make it easy to pick out these lines.
     A number of other events are also recorded in the main log. Some
     of these entries can be suppressed by changing the value of the
     "log_level" and "log_queue_run_level" configuration options.
     There are also a number of options whose names start with "log_"
     which can be used to request additional logging.

   * The reject log records information from messages that are rejected
     as a result of a configuration option (that is, for policy
     reasons). If the message's header has been read, its contents are
     written to this log, following a copy of the one-line message that
     is also written to the main log.

   * The panic log is written when Exim suffers a disastrous error.
     Often (but not always) it bombs out afterwards. The panic log
     should be checked regularly to pick up any problems. When Exim
     cannot open its panic log, it tries as a last resort to write to
     the system log (syslog). This is opened with LOG_PID+LOG_CONS and
     the facility code of LOG_MAIL. The message itself is written at
     priority LOG_CRIT.

The logs may be written to local files, or to syslog, or both. However,
it should be noted that many syslog implementations use UDP as a
transport, and are therefore unreliable in the sense that messages are
not guaranteed to arrive at the loghost, nor is the ordering of
messages necessarily maintained.  It has also been reported that on
large log files (tens of megabytes) you may need to tweak syslog to
prevent it syncing the file with each write - on Linux this has been
seen to make syslog take 90% plus of CPU time.

The destination for Exim's logs is configured by setting LOG_FILE_PATH
in `Local/Makefile' or by setting "log_file_path" in the run time
configuration.  This latter string is expanded, so it can contain, for
example, references to the host name:

     log_file_path = /var/log/$primary_hostname/exim_%slog

It is generally advisable, however, to set the string in
`Local/Makefile' rather than at run time, because then the setting is
available right from the start of Exim's execution. Otherwise, if
there's something it wants to log before it has read the configuration
file (for example, an error in the configuration file) it will not use
the path you want, and may not be able to log at all.

The value of LOG_FILE_PATH or "log_file_path" is a colon-separated
list, currently limited to at most two items.  This is one option where
the facility for changing a list separator may not be used. The list
must always be colon-separated.  If an item in the list is `syslog'
then syslog is used; otherwise the item must either be an absolute
path, containing `%s' at the point where `main', `reject', or `panic'
is to be inserted, or be empty, implying the use of the default path,
which is `log/%slog' in the spool directory. The default path is used
if nothing is specified. Here are some examples of possible settings:

     LOG_FILE_PATH=syslog                      syslog only
     LOG_FILE_PATH=:syslog                     syslog and default path
     LOG_FILE_PATH=syslog : /usr/log/exim_%s   syslog and specified path
     LOG_FILE_PATH=/usr/log/exim_%s            specified path only

If there are more than two paths in the list, the first is used and a
panic error is logged.



* Menu:

* Logging to local files::
* Logging to syslog::
* Logging message reception::
* Logging deliveries::
* Deferred deliveries::
* Delivery failures::
* Fake deliveries::
* Completion::
* Other log entries::
* Log level::
* Message log::


File: exim.info,  Node: Logging to local files,  Next: Logging to syslog,  Prev: Log files,  Up: Log files

Logging to local files
======================

A utility script called "exicyclog" which renames and compresses the
main and reject logs each time it is called is provided for use with
logs written to local files. The maximum number of old logs to keep can
be set. It is suggested this is run as a daily "cron" job. A Perl
script called "eximstats" which does simple analysis of main log files
is also provided. See chapter "Exim utilities" for details of both
these utilities.

An Exim delivery process opens the main log when it first needs to
write to it, and it keeps the file open in case subsequent entries are
required - for example, if a number of different deliveries are being
done for the same message. However, remote SMTP deliveries can take a
long time, and this means that the file may be kept open long after it
is renamed if "exicyclog" or something similar is being used to rename
log files on a regular basis. To ensure that a switch of log files is
noticed as soon as possible, Exim calls "stat()" on the main log's name
before reusing an open file, and if the file does not exist, or its
inode has changed, the old file is closed and Exim tries to open the
main log from scratch. Thus, an old log file may remain open for quite
some time, but no Exim processes should write to it once it has been
renamed.


File: exim.info,  Node: Logging to syslog,  Next: Logging message reception,  Prev: Logging to local files,  Up: Log files

Logging to syslog
=================

The use of syslog does not change what Exim logs or the format of its
messages.  The same strings are written to syslog as to log files. The
syslog `facility' is set to LOG_MAIL, and the program name to `exim'.
On systems that permit it (all except ULTRIX) the LOG_PID flag is set
so that the "syslog()" call adds the pid as well as the time and host
name to each line. The three log streams are mapped onto syslog
priorities as follows:

   - "mainlog" is mapped to LOG_INFO

   - "rejectlog" is mapped to LOG_NOTICE

   - "paniclog" is mapped to LOG_ALERT

Many log lines are written to both "mainlog" and "rejectlog", so there
will be duplicates if these are routed by syslog to the same place.

Exim's log lines can sometimes be very long, and some of its "rejectlog"
entries contain multiple lines when headers are included. To cope with
both these cases, entries written to syslog are split into separate
"syslog()" calls at each internal newline, and also after a maximum of
1000 characters. To make it easy to re-assemble them later, each
component of a split entry starts with a string of the form `[<n>/<m>]'
or `[<n>\<m>]' where <n> is the component number and <m> is the total
number of components in the entry. The / delimiter is used when the
line was split because it was too long; if it was split because of an
internal newline, the \ delimiter is used. For example, supposing the
length limit to be 70 instead of 1000, the following would be the
result of a typical rejection message to "mainlog" (LOG_INFO), each
line in addition being preceded by the time, host name, and pid as
added by syslog:

     $smc{[1/3] 1999-09-16 16:09:43 11RdAL-0006pc-00 rejected from [127.0.0.1] (ph10):
     [2/3]  syntax error in 'From' header when scanning for sender: missing or ma
     [3/3] lformed local part in "<>" (envelope sender is <ph10@cam.ac.uk>)}

The same error might cause the following lines to "rejectlog"
(LOG_NOTICE):

     $smc{[1/14] 1999-09-16 16:09:43 11RdAL-0006pc-00 rejected from [127.0.0.1] (ph10):
     [2/14]  syntax error in 'From' header when scanning for sender: missing or ma
     [3\14] lformed local part in "<>" (envelope sender is <ph10@cam.ac.uk>)
     [4\14] Recipients: ph10@some.domain.cam.ac.uk
     [5\14] P Received: from [127.0.0.1] (ident=ph10)
     [6\14]        by xxxxx.cam.ac.uk with smtp (Exim 3.10 #27)
     [7\14]        id 11RdAL-0006pc-00
     [8\14]        for ph10@cam.ac.uk; Thu, 16 Sep 1999 16:09:43 +0100
     [9\14] F From: <>
     [10\14]   Subject: this is a test header
     [11\14]   X-something: this is another header
     [12\14] I Message-Id: <E11RdAL-0006pc-00@xxxxx.cam.ac.uk>
     [13\14] B Bcc:
     [14/14]   Date: Thu, 16 Sep 1999 16:09:43 +0100}

Log lines that are neither too long nor contain newlines are written to
syslog without modification, for example:

     1999-09-16 16:09:47 SMTP connection from [127.0.0.1] closed by QUIT

The times added by syslog are normally the same as Exim's time stamps
(though in a different format, and without the year) but can sometimes
be different.

If only syslog is being used, the Exim monitor is unable to provide a
log tail display, unless syslog is routing "mainlog" to a file on the
local host and the environment variable EXIMON_LOG_FILE_PATH is set to
tell the monitor where it is.


File: exim.info,  Node: Logging message reception,  Next: Logging deliveries,  Prev: Logging to syslog,  Up: Log files

Logging message reception
=========================

The format of the single-line entry in the main log that is written for
every message received is shown in the example below, which is split
over several lines in order to fit it on the page:

     1995-10-31 08:57:53 0tACW1-0005MB-00 <= kryten@dwarf.fict.book
       H=mailer.fict.book [123.123.123.123] U=exim
       P=smtp S=5678 id=<incoming message id>

The H and U fields identify the remote host and record the RFC 1413
identity of the user that sent the message, if one was received. The
number given in square brackets is the IP address of the sending host.
If there is just a single host name in the H field, as above, it has
been verified to correspond to the IP address (see the "host_lookup"
option). If the name is in parentheses, it was the name quoted by the
remote host in the SMTP HELO or EHLO command, and has not been
verified. If verification yields a different name to that given for
HELO or EHLO, the verified name appears first, followed by the HELO or
EHLO name in parentheses.

Misconfigured hosts (and mail forgers) sometimes put an IP address,
with or without brackets, in the HELO or EHLO command, leading to
entries in the log containing things like

     H=(10.21.32.43) [123.99.8.34]
     H=([10.21.32.43]) [123.99.8.34]

which can be confusing. Only the final address in square brackets can
be relied on. For locally generated messages, the H field is omitted,
and the U field contains the login name of the caller of Exim.

For all messages, the P field specifies the protocol used to receive the
message. This is set to `asmtp' for messages received from hosts which
have authenticated themselves using the SMTP AUTH command. In this case
there is an additional item A= followed by the name of the
authenticator that was used.  If an authenticated identification was
set up by the authenticator's "server_set_id" option, this is logged
too, separated by a colon from the authenticator name.

The id field records the existing message id, if present.  The size of
the received message is given by the S field. When the message is
delivered, headers may get removed or added, so that the size of
delivered copies of the message may not correspond with this value (and
indeed may be different to each other).

If the "log_received_sender" option is on, the unrewritten original
sender of a message is added to the end of the log line that records
the message's arrival, after the word `from'.  If the
"log_received_recipients" option is on, a list of all the recipients of
a message is added to the log line, preceded by the word `for'. This
happens after any unqualified addresses are qualified, but before any
rewriting is done.  If the "log_subject" option is on, the subject of
the message is added to the log line, preceded by `T=' (T for `topic',
since S is already used for `size').

A delivery error message is shown with the sender address `<>', and if
it is a locally-generated error message, this is normally followed by
an item of the form

     R=<message id>

which is a reference to the local identification of the message that
caused the error message to be sent.


File: exim.info,  Node: Logging deliveries,  Next: Deferred deliveries,  Prev: Logging message reception,  Up: Log files

Logging deliveries
==================

The format of the single-line entry in the main log that is written for
every delivery is shown in one of the examples below, for local and
remote deliveries, respectively. Each example has been split into two
lines in order to fit it on the page:

     1995-10-31 08:59:13 0tACW1-0005MB-00 => marv <marv@hitch.fict.book>
       D=localuser T=local_delivery
     1995-10-31 09:00:10 0tACW1-0005MB-00 => monk@holistic.fict.book
       R=lookuphost T=smtp H=holistic.fict.book [234.234.234.234]

For ordinary local deliveries, the original address is given in angle
brackets after the final delivery address, which might be a pipe or a
file. If intermediate address(es) exist between the original and the
final address, the last of these is given in parentheses after the
final address.  However, "log_all_parents" can be set to cause all
intermediate addresses to be logged.

If a shadow transport was run after a successful local delivery, the
log line for the successful delivery has an item added on the end, of
the form

     ST=<shadow transport name>

If the shadow transport did not succeed, the error message is put in
parentheses afterwards.

When a local delivery occurs as a result of routing rather than
directing (for example, messages are being batched up for transmission
by some other means), the log entry looks more like that for a remote
delivery.

For normal remote deliveries, if the "log_smtp_confirmation" option is
on, the response to the final `.' in the SMTP transmission is added to
the log line, preceded by `C='. If the final delivery address is not
the same as the original address (owing to changes made by routers),
the original is shown in angle brackets.

The generation of a reply message by a filter file gets logged as a
`delivery' to the addressee, preceded by `>'. The D and T items record
the director and transport. For remote deliveries, the router,
transport, and host are recorded.

When more than one address is included in a single delivery (for
example, two SMTP RCPT commands in one transaction) then the second and
subsequent addresses are flagged with `->' instead of `=>'. When two or
more messages are delivered down a single SMTP connection, an asterisk
follows the IP address in the log lines for the second and subsequent
messages.

When the -N debugging option is used to prevent delivery from actually
occurring, log entries are flagged with `*>' instead of `=>'.

When a message is discarded as a result of the command `seen finish'
being obeyed in a filter file which generates no deliveries, a log
entry of the form

     1998-12-10 00:50:49 0znuJc-0001UB-00 => discarded
       <low.club@trick4.bridge> D=userforward

is written, to record why no deliveries are logged.


File: exim.info,  Node: Deferred deliveries,  Next: Delivery failures,  Prev: Logging deliveries,  Up: Log files

Deferred deliveries
===================

When a delivery is deferred, a line of the following form is logged:

     1995-12-19 16:20:23 0tRiQz-0002Q5-00 == marvin@endrest.book
       T=smtp defer (146): Connection refused

In the case of remote deliveries, the error is the one that was given
for the last IP address that was tried. Details of individual SMTP
failures are also written to the log, so the above line would be
preceded by something like

     1995-12-19 16:20:23 0tRiQz-0002Q5-00 Failed to connect to endrest.book
       [239.239.239.239]: Connection refused

When a deferred address is skipped because its retry time has not been
reached, a message is written to the log, but this can be suppressed by
changing the "log_level" option.


File: exim.info,  Node: Delivery failures,  Next: Fake deliveries,  Prev: Deferred deliveries,  Up: Log files

Delivery failures
=================

If a delivery fails, a line of the following form is logged:

     1995-12-19 16:20:23 0tRiQz-0002Q5-00 ** jim@trek99.film
       <jimtrek99.film>: unknown mail domain

This is followed (eventually) by a line giving the address to which the
delivery error has been sent.


File: exim.info,  Node: Fake deliveries,  Next: Completion,  Prev: Delivery failures,  Up: Log files

Fake deliveries
===============

If a delivery does not actually take place because the -N option has
been used to suppress it, an apparently normal delivery line is written
to the log, except that `=>' is replaced by `*>'.


File: exim.info,  Node: Completion,  Next: Other log entries,  Prev: Fake deliveries,  Up: Log files

Completion
==========

A line of the form

     1995-10-31 09:00:11 0tACW1-0005MB-00 Completed

is written to the main log when a message is about to be removed from
the spool at the end of its processing.


File: exim.info,  Node: Other log entries,  Next: Log level,  Prev: Completion,  Up: Log files

Other log entries
=================

Various other types of log entry are written from time to time. Most
should be self-explanatory. Among the more common are:

   * "retry time not reached"  An address previously suffered a
     temporary error during directing or routing or local delivery, and
     the time to retry it has not yet arrived.

   * "retry time not reached for any host"  An address previously
     suffered temporary errors during remote delivery, and the retry
     time has not yet arrived for any of the hosts to which it is
     routed.

   * "spool file locked"  An attempt to deliver a message cannot
     proceed because some other Exim process is already working on the
     message. This can be quite common if queue running processes are
     started at frequent intervals. The "exiwhat" utility script can be
     used to find out what Exim processes are doing.


File: exim.info,  Node: Log level,  Next: Message log,  Prev: Other log entries,  Up: Log files

Log level
=========

The "log_level" configuration option controls the amount of data
written to the main log. The higher the number, the more is written. A
value of 6 causes all possible messages to appear, though higher levels
may get defined in the future. Zero sets a minimal level of logging,
with higher levels adding the following, successively:

     1   rejections because of policy
         re-addressing by the system filter
     
     2   $t rejections because of message size
     
     3   $t verification failures
     
     4   $t SMTP timeouts
         SMTP connection refusals because too busy
         SMTP unexpected connection loss
         SMTP (dis)connections when "log_smtp_connections" is set
         SMTP syntax errors when "log_smtp_syntax_errors" is set
         non-immediate delivery of SMTP messages because of load level,
         or number of connections etc.
     
     5   $t `retry time not reached [for any host]'
         `spool file locked' (i.e. some other process is delivering the message)
         `message is frozen' (when skipping it in a queue run)
         `error message sent to ...'
     
     6   $t invalid HELO and EHLO arguments (see "helo_verify")

The default log level is 5, which is on the verbose side. Rejection
information is still written to the reject log in all cases.


File: exim.info,  Node: Message log,  Prev: Log level,  Up: Log files

Message log
===========

In addition to the four main log files, Exim writes a log file for each
message that it handles. The names of these per-message logs are the
message ids, and they are kept in the "msglog" sub-directory of the
spool directory. A single line is written to the message log for each
delivery attempt for each address.  It records either a successful
delivery, or the reason (temporary or permanent) for failure. If the
log level is 5 or higher, `retry time not reached' messages are also
written to individual message logs.  If the log level is 4 or less,
they are suppressed after the first delivery attempt.

When a local part is expanded by aliasing or a forwarding file, a line
is written to the message log when all its child deliveries are
completed. SMTP connection failures for each remote host are also
logged here. The log is deleted when processing of the message is
complete, unless "preserve_message_logs" is set, but this should be
used only with great care because they can fill up your disc very
quickly.


File: exim.info,  Node: Day-to-day management,  Next: Exim utilities,  Prev: Log files,  Up: Top

Day-to-day management
*********************

This chapter describes some of the regular tasks that need to be done
to keep Exim running smoothly.



* Menu:

* The panic log::
* The reject log::
* Log cycling::
* Statistics::
* What is Exim doing?::
* Changing the configuration::
* Watching the queue::
* Holding domains::


File: exim.info,  Node: The panic log,  Next: The reject log,  Prev: Day-to-day management,  Up: Day-to-day management

The panic log
=============

When certain disasters occur, Exim writes entries to its panic log.
These are often copied to the main log as well, but can get lost amid
the mass of other entries. The panic log should be empty under normal
circumstances. It is therefore a good idea to check it (or to have a
"cron" script check it) regularly, in order to become aware of any
problems.


File: exim.info,  Node: The reject log,  Next: Log cycling,  Prev: The panic log,  Up: Day-to-day management

The reject log
==============

If checking of sender addresses on incoming mail is enabled, the
headers of rejected messages are written to the reject log. Other
policy rejections also cause entries in this log, which should be
regularly inspected to ensure that the checking is working properly,
and to pick up errors such as missing DNS entries.


File: exim.info,  Node: Log cycling,  Next: Statistics,  Prev: The reject log,  Up: Day-to-day management

Log cycling
===========

The "exicyclog" script (see chapter "Exim utilities") cycles the names
of log files, compresses all but the most recent, and deletes the
oldest. This should be run at intervals dependent on the amount of mail
traffic. For a system with a reasonable amount of mail, running it
daily via "cron" is suggested.


File: exim.info,  Node: Statistics,  Next: What is Exim doing?,  Prev: Log cycling,  Up: Day-to-day management

Statistics
==========

The "eximstats" script (see chapter "Exim utilities") produces
statistics about messages received and delivered, by analysing log
files.


File: exim.info,  Node: What is Exim doing?,  Next: Changing the configuration,  Prev: Statistics,  Up: Day-to-day management

What is Exim doing?
===================

On systems that can restart a system call after receiving a signal, Exim
responds to the SIGUSR1 signal by writing a line describing what it is
doing to the file "exim-process.info" in its spool directory.  The
"exiwhat" script (see chapter "Exim utilities") sends the signal to all
Exim processes it can find, having first emptied the file.  It then
waits for one second to allow the Exim processes to react before
displaying the results. In order to run "exiwhat" successfully you have
to have sufficient privilege to send the signal to the Exim processes,
so it is normally run as root.

When the number of processes handling incoming SMTP calls is limited by
setting the "smtp_accept_max" option, the daemon uses the SIGCHLD
signal to detect when any of its subprocesses finishes. On some
operating systems this signal sometimes gets lost when the system is
very busy.  However, Exim's daemon cleans up subprocesses every time it
wakes up, so even if SIGCHLD doesn't happen, the completion of
subprocesses should eventually get noticed.


File: exim.info,  Node: Changing the configuration,  Next: Watching the queue,  Prev: What is Exim doing?,  Up: Day-to-day management

Changing the configuration
==========================

A changed configuration file is picked up immediately by any Exim
processes that are subsequently started, and by any existing process
that re-execs Exim, but it will not be noticed by any existing
processes. The daemon process can be caused to restart itself by
sending it the SIGHUP signal, which should also be sent when a new
version of the Exim binary is installed.  SIGHUP causes the daemon to
close down, and then re-exec Exim, thus causing it to re-read the
configuration file.

The current process id is written to a file whose name depends on the
type of daemon being run. By default, the file is written in Exim's
spool directory, but a compile-time configuration of PID_FILE_PATH can
be used to cause it to be placed elsewhere. When the daemon is both
listening for incoming SMTP on the standard port and periodically
starting queue runner processes, the file is called "exim-daemon.pid".
If it is doing only one of these things, the option that started it
(either -bd or -q<time>) is added to the file name. It is not necessary
to use SIGHUP when changing the contents of any files referred to in
the configuration (for example, alias files) since each delivery
process reads such files independently.


File: exim.info,  Node: Watching the queue,  Next: Holding domains,  Prev: Changing the configuration,  Up: Day-to-day management

Watching the queue
==================

The queue of messages awaiting delivery can be examined by running the
Exim monitor (see chapter "The Exim monitor"), or by obeying "exim -bp"
(or its variants) periodically. The "exiqsumm" utility script can be
called to obtain a summary of the waiting messages for each domain,
sorted by domain, age, or message count.

If any messages are frozen, their header files and message log files
should be examined to determine the cause of the problem. Once the
problem is believed to be fixed, the messages can be unfrozen by the
administrator, who can also kick off an immediate delivery attempt, and
also change recipient and sender addresses if necessary.  There are a
number of command line options whose names begin with -M for doing
these things, and they can also be done from the Exim monitor.


File: exim.info,  Node: Holding domains,  Prev: Watching the queue,  Up: Day-to-day management

Holding domains
===============

The option "hold_domains" allows mail for particular domains to be held
on the queue manually. This option is intended as a temporary
operational measure for delaying the delivery of mail while some
problem is being sorted out, or some new configuration tested.


File: exim.info,  Node: Exim utilities,  Next: The Exim monitor,  Prev: Day-to-day management,  Up: Top

Exim utilities
**************

A number of utility scripts and programs are supplied with Exim. Most
of them are built as part of the normal building process, but the log
file analyser is entirely free-standing.



* Menu:

* Querying Exim processes::
* Summarising the queue::
* Extracting log information::
* Cycling log files::
* Making DBM files::
* Individual retry times::
* Database maintenance::
* Mail statistics::
* Mailbox maintenance::
* Mailbox maintenance (continued)::


File: exim.info,  Node: Querying Exim processes,  Next: Summarising the queue,  Prev: Exim utilities,  Up: Exim utilities

Querying Exim processes
=======================

The shell script called "exiwhat" first of all empties the file
"exim-process.info" in Exim's spool directory.  It then uses the "ps"
command to find all processes running exim, and sends each one the
SIGUSR1 signal. This causes each process to write a single line
describing its current activity to the file. The script waits for one
second to allow the Exim processes to react, then copies the file to the
standard output.

Unfortunately, the "ps" command varies between different versions of
Unix. Not only are different options used, but the format of the output
is different. For this reason, there are some system configuration
options that configure exactly how "exiwhat" works. If it doesn't seem
to be working for you, check the following compile-time options:

     EXIWHAT_PS_CMD     the command for running "ps"
     EXIWHAT_PS_ARG     the argument for "ps"
     EXIWHAT_EGREP_ARG  the argument for "egrep" to select from "ps" output
     EXIWHAT_KILL_ARG   the argument for the "kill" command

This facility is available only in operating systems where a signal
handler can be set up such that an interrupted system call is resumed
when the signal handler has finished. An example of typical output from
"exiwhat" is

       164 daemon: -q1h, listening on port 25
     10483 running queue: waiting for 0tAycK-0002ij-00 (10492)
     10492 delivering 0tAycK-0002ij-00 to mail.ref.book [42.42.42.42]
       (editor@ref.book)
     10592 handling incoming call from [245.211.243.242]
     10628 accepting a local non-SMTP message

The first number in the output line is the process number.  The third
line has been split here, in order to fit it on the page. Because Exim
processes run under a variety of uids, it is necessary to run "exiwhat"
as root in order to be able to send the signal to all Exim processes.


File: exim.info,  Node: Summarising the queue,  Next: Extracting log information,  Prev: Querying Exim processes,  Up: Exim utilities

Summarising the queue
=====================

The "exiqsumm" utility is a Perl script, provided in the "util"
directory, which reads the output of "exim -bp" and produces a summary
of the messages by outputting a line like the following for each domain:

       3   2322   74m   66m  msn.com

This contains the number of messages for that domain, their total
volume, and the length of time the oldest and the newest have been
waiting. By default the output is sorted on the domain name, but
"exiqsumm" has the options -a and -c, which cause it to be sorted by
oldest message and by count of messages, respectively.

The output of "exim -bp" is based on the original addresses in the
message, so no addresses generated by aliasing or forwarding are
included. Consequently this applies also to the output from "exiqsumm".


File: exim.info,  Node: Extracting log information,  Next: Cycling log files,  Prev: Summarising the queue,  Up: Exim utilities

Extracting log information
==========================

The "exigrep" utility is a Perl script, provided in the "util"
directory, that extracts from one or more log files all entries
relevant to any message whose log entries contain at least one that
matches a given pattern. The pattern match is case-insensitive. Thus
one can search for all mail for a given user or a given host, for
example. The usage is:

     exigrep [-l] <pattern> [<log file>] ...

where the -l flag means `literal', that is, treat all characters in the
pattern as standing for themselves. Otherwise the pattern must be a Perl
regular expression. If no file names are given on the command line, the
standard input is read.

If the location of a "zcat" command is known from the definition of
ZCAT_COMMAND in `Local/Makefile', "exigrep" automatically passes any
file whose name ends in COMPRESS_SUFFIX through "zcat" as it searches
it.


File: exim.info,  Node: Cycling log files,  Next: Making DBM files,  Prev: Extracting log information,  Up: Exim utilities

Cycling log files
=================

The "exicyclog" script can be used to cycle "mainlog" and "rejectlog"
files that have been written to local disc. This is not necessary if
only syslog is being used. Some operating systems have their own
standard scripts for log cycling, and these can be used instead of
"exicyclog" if preferred.

Each time "exicyclog" is run the files get `shuffled down' by one. If
the main log file name is "mainlog" (the default) then when "exicyclog"
is run "mainlog" becomes "mainlog.01", the previous "mainlog.01"
becomes "mainlog.02" and so on, up to a limit which is set in the
script, and which defaults to 10.

In versions of Exim prior to 1.90, "exicyclog" used single-digits for
numbers less than ten. This was changed to make the files list in a
more natural order.  The script contains conversion code. If it finds a
file called "mainlog.1" it attempts to rename all files in the old form
to the new form.

If no "mainlog" file exists, the script does nothing. Reject logs are
handled similarly. Files that `drop off' the end are deleted. All files
with numbers greater than 01 are compressed, using a compression
command which is configured by the COMPRESS_COMMAND setting in
`Local/Makefile'.

It is usual to run "exicyclog" daily from a "crontab" entry of the form

     1 0 * * *  /opt/exim/bin/exicyclog

In this way, each day's log is (mostly) in a separate file. There will
be some overlap from processes that have the log open at the time of
renaming.

The "exicyclog" script can be run as the Exim user when one is defined,
because the log files will be owned by that user in that case.
Otherwise it has to be run as root.


File: exim.info,  Node: Making DBM files,  Next: Individual retry times,  Prev: Cycling log files,  Up: Exim utilities

Making DBM files
================

The "exim_dbmbuild" program reads an input file in the format of an
alias file (see chapter "The aliasfile director") and writes a DBM
database using the lower-cased alias names as keys and the remainder of
the information as data. The lower-casing can be prevented by calling
the program with the -nolc option.

A terminating zero is included as part of the key string. This is
expected by the "dbm" lookup type. However, if the option -nozero is
given, "exim_dbmbuild" creates files without terminating zeroes in
either the key strings or the data strings. The "dbmnz" lookup type can
be used with such files.

The program requires two arguments: the name of the input file (which
can be a single hyphen to indicate the standard input), and the name of
the output database. It creates the database under a temporary name,
and then renames the file(s) if all went well.  If the native DB
interface is in use (USE_DB is set in a compile-time configuration file
- this is common in free versions of Unix) the two file names must be
different, because in this mode the Berkeley DB functions create a
single output file using exactly the name given. For example:

     exim_dbmbuild /etc/aliases /etc/aliases.db

reads the system alias file and creates a DBM version of it in
"/etc/aliases.db".

In systems that use the "ndbm" routines (mostly proprietary versions of
Unix), DBM databases consist of two files with suffixes ".dir" and
".pag". In this environment, the suffixes are added to the second
argument of "exim_dbmbuild", so it can be the same as the first. This
is also the case when the Berkeley functions are used in compatibility
mode (though this is not recommended), because in that case it adds a
".db" suffix to the file name.

The program outputs a warning if it encounters a duplicate key, and
when it finishes, its return code is 1 rather than zero, unless the
-noduperr option is used. By default, only the first of a set of
duplicates is used - this makes it compatible with "lsearch" lookups.
There is an option -lastdup which causes it to use the data for the
last duplicate instead. There is also an option -nowarn, which stops it
listing duplicate keys to "stderr". For other errors, where it doesn't
actually make a new file, the return code is 2.


File: exim.info,  Node: Individual retry times,  Next: Database maintenance,  Prev: Making DBM files,  Up: Exim utilities

Individual retry times
======================

A utility called "exinext" (mostly a Perl script) provides the ability
to fish specific information out of the retry database. Given a mail
domain (or a complete address), it looks up the hosts for that domain,
and outputs any retry information. At present, the retry information is
obtained by running "exim_dumpdb" (see below) and post-processing the
output.  For example:

     exinext piglet@milne.fict.book
     kanga.milne.fict.book:100.100.8.1 error 146: Connection refused
       first failed: 21-Feb-1996 14:57:34
       last tried:   21-Feb-1996 14:57:34
       next try at:  21-Feb-1996 15:02:34
     roo.milne.fict.book:100.100.8.3 error 146: Connection refused
       first failed: 20-Jan-1996 13:12:08
       last tried:   21-Feb-1996 11:42:03
       next try at:  21-Feb-1996 19:42:03
       past final cutoff time

You can also give "exinext" a local "local_part", without a domain, and
it will give any retry information for it.  Also, a message id can be
given to obtain retry information pertaining to a specific message.
This exists only when an attempt to deliver a message to a remote host
suffers a message-specific error (see section "Errors in outgoing SMTP"
in chapter "SMTP processing").  "Exinext" is not particularly
efficient, but then it isn't expected to be run very often.


File: exim.info,  Node: Database maintenance,  Next: Mail statistics,  Prev: Individual retry times,  Up: Exim utilities

Database maintenance
====================

Three utility programs are provided for maintaining the DBM files that
Exim uses to contain its delivery hint information. Each program
requires two arguments. The first specifies the name of Exim's spool
directory, and the second is the name of the database it is to operate
on. These are as follows:

   * "retry": the database of retry information

   * "reject": the database of information about rejected messages

   * "wait-<transport name>": databases of information about messages
     waiting for remote hosts

   * "serialize-<transport name>": databases of information about
     current connections to hosts which are restricted to one
     connection at a time

   * "serialize-etrn-runs": database of information about current queue
     runs started by the ETRN command when "smtp_etrn_serialize" is set.

The entire contents of a database are written to the standard output by
the "exim_dumpdb" program, which has no options or arguments other than
the spool and database names. For example, to dump the retry database:

     exim_dumpdb /var/spool/exim retry

Two lines of output are produced for each entry:

       T:mail.ref.book:242.242.242.242 146 77 Connection refused
     31-Oct-1995 12:00:12  02-Nov-1995 12:21:39  02-Nov-1995 20:21:39 *

The first item on the first line is the key of the record. It starts
with one of the letters D, R, or T, depending on whether it refers to a
directing, routing, or transport retry. For a local delivery, the next
part is the local address; for a remote delivery it is the name of the
remote host, followed by its failing IP address. Then there follows an
error code, an additional error code, and a textual description of the
error.

The three times on the second line are the time of first failure, the
time of the last delivery attempt, and the computed time for the next
attempt. The line ends with an asterisk if the cutoff time for the last
retry rule has been exceeded.

Each output line from "exim_dumpdb" for the reject database consists of
a date and time, followed by the letter T or F and a fixed point
number, followed by the address that was rejected, followed either by
the name of the host that sent the bad address, if this has been
verified, or otherwise the IP address. The letter is F if only one
previous rejection of this address (from this host) has been done
recently, and T if a second has occurred, causing rejection of the MAIL
command, and subsequently rejection of the RCPT commands. The fixed
point number is zero when the last rejection was a permanent one.
Otherwise it records the rate of temporary rejections for the same
address from the same host, per hour.

Each output line from "exim_dumpdb" for the "wait-xxx" databases
consists of a host name followed by a list of ids for messages that are
or were waiting to be delivered to that host. If there are a very large
number for any one host, continuation records, with a sequence number
added to the host name, may be seen. The data in these records is often
out of date, because a message may be routed to several alternative
hosts, and Exim makes no effort to keep cross-references.

Each output line from "exim_dumpdb" for the "serialize-smtp" database
consists of a host name preceded by the time that Exim made a
connection to that host.  Exim keeps track of connections only for
those hosts or networks that have been configured for serialization.

The "exim_tidydb" utility program is used to tidy up the contents of
the hints databases. If run with no options, it removes all records
from a database that are more than 30 days old. The cutoff date can be
altered by means of the -t option, which must be followed by a time.
For example, to remove all records older than a week from the retry
database:

     exim_tidydb -t 7d /var/spool/exim retry

For the "wait-xxx" and "retry" databases, the -f option can also be
used. Both these databases contain items that involve message ids. In
the former these appear as data in records keyed by host - they were
messages that were waiting for that host - and in the latter they are
the keys for retry information for messages that have suffered certain
types of error. When -f is used, a check is made to ensure that message
ids in database records are those of messages that are still on the
queue. Message ids for messages that no longer exist are removed from
"wait-xxx" records, and if this leaves any records empty, they are
deleted. For the "retry" database, -f causes the removal of records
whose keys are non-existent message ids. For other types of database,
-f has no effect.

The "exim_tidydb" utility outputs comments on the standard output
whenever it removes information from the database. It is suggested that
it be run periodically on all the hints databases, but at a quiet time
of day, since it requires a database to be locked (and therefore
inaccessible to Exim) while it does its work.

The "exim_fixdb" program is a utility for interactively modifying
databases.  Its main use is for testing Exim, but it might also be
occasionally useful for getting round problems in a live system. It has
no options, and its interface is somewhat crude. On entry, it prompts
for input with a right angle-bracket. A key of a database record can
then be entered, and the data for that record is displayed.

If `d' is typed at the next prompt, the entire record is deleted. For
all except the "retry" database, that is the only operation that can be
carried out. For the "retry" database, each field is output preceded by
a number, and data for individual fields can be changed by typing the
field number followed by new data, for example:

     > 4 951102:1000

resets the time of the next delivery attempt. Time values are given as a
sequence of digit pairs for year, month, day, hour, and minute. Colons
can be used as optional separators.


File: exim.info,  Node: Mail statistics,  Next: Mailbox maintenance,  Prev: Database maintenance,  Up: Exim utilities

Mail statistics
===============

A Perl script called "eximstats" is supplied in the "util" directory.
This has been hacked about quite a bit over time. It now gives quite a
lot of information by default, but there are options for suppressing
various parts of it. Following any options, the arguments to the script
are a list of files, which should be main log files.

"Eximstats" extracts information about the number and volume of messages
received from or delivered to various hosts. The information is sorted
both by message count and by volume, and the top fifty hosts in each
category are listed on the standard output. For messages delivered and
received locally, similar statistics are produced per user.

The output also includes total counts and statistics about delivery
errors, and histograms showing the number of messages received and
deliveries made in each hour of the day. A delivery with more than one
address in its `envelope' (for example, an SMTP transaction with more
than one RCPT command) is counted as a single delivery by "eximstats".

Though normally more deliveries than receipts are reported (as messages
may have multiple recipients), it is possible for "eximstats" to report
more messages received than delivered, even though the spool is empty
at the start and end of the period in question. If an incoming message
contains no valid recipients, no deliveries are recorded for it. An
error report is handled as an entirely separate message.

"Eximstats" always outputs a grand total summary giving the volume and
number of messages received and deliveries made, and the number of
hosts involved in each case. It also outputs the number of messages
that were delayed (that is, not completely delivered at the first
attempt), and the number that had at least one address that failed.

The remainder of the output is in sections that can be independently
disabled or modified by various options. It consists of a summary of
deliveries by transport, histograms of messages received and delivered
per time interval (default per hour), information about the time
messages spent on the queue, a list of relayed messages, lists of the
top fifty sending hosts, local senders, destination hosts, and
destination local users by count and by volume, and a list of delivery
errors that occurred.

The relay information lists messages that were actually relayed, that
is, they came from a remote host and were directly delivered to some
other remote host.  A delivery that is considered as a relay by the
checking features described in section "Control of relaying" in chapter
"Other policy controls on incoming mail", because its domain is not in
"local_domains", might still end up being delivered locally under some
configurations, and if this happens it doesn't show up as a relay in
the "eximstats" output.

The options for "eximstats" are as follows:



* Menu:

* -nt::
* -h<n>::
* -q0::
* -q<n1>::
* -nr::
* -nr/pattern/::
* -t<n>::
* -tnl::
* -ne::


File: exim.info,  Node: -nt,  Next: -h<n>,  Prev: Mail statistics,  Up: Mail statistics

-nt _option_
------------

Suppress the statistics about delivery by transport.


File: exim.info,  Node: -h<n>,  Next: -q0,  Prev: -nt,  Up: Mail statistics

-h<n> _option_
--------------

This option controls the histograms of messages received and deliveries
per time interval. By default the time interval is one hour. If -h0 is
given, the histograms are suppressed; otherwise the value of <n> gives
the number of divisions per hour, so -h2 sets an interval of 30
minutes, and the default is equivalent to -h1.


File: exim.info,  Node: -q0,  Next: -q<n1>,  Prev: -h<n>,  Up: Mail statistics

-q0 _option_
------------

Suppress information about times messages spend on the queue.


File: exim.info,  Node: -q<n1>,  Next: -nr,  Prev: -q0,  Up: Mail statistics

-q<n1> _option_
---------------

This option sets an alternative list of time intervals for the queueing
information. The values are separated by commas and are in seconds, but
can involve arithmetic multipliers, so for example you can set 3*60 to
specify 3 minutes. A setting such as

     -q60,5*60,10*60

causes "eximstats" to give counts of messages that stayed on the queue
for less than one minute, less than five minutes, less than ten
minutes, and over ten minutes.


File: exim.info,  Node: -nr,  Next: -nr/pattern/,  Prev: -q<n1>,  Up: Mail statistics

-nr _option_
------------

Suppress information about messages relayed through this host.


File: exim.info,  Node: -nr/pattern/,  Next: -t<n>,  Prev: -nr,  Up: Mail statistics

-nr/pattern/ _option_
---------------------

Suppress information about relayed messages that match the pattern,
which is matched against a string of the following form (split over two
lines here in order to fit it on the page):

     H=<host> [<ip address>] A=<sender address> =>
       H=<host> A=<recipient address>

for example

     H=in.host [1.2.3.4] A=from@some.where =>
       H=out.host A=to@else.where

The sending host name appears in parentheses if it has not been
verified as matching the IP address.  The mail addresses are taken from
the envelope, not the headers. This option allows you to screen out
hosts whom you are happy to have using your host as a relay.


File: exim.info,  Node: -t<n>,  Next: -tnl,  Prev: -nr/pattern/,  Up: Mail statistics

-t<n> _option_
--------------

Sets the `top' count to <n>. This controls the listings of the `top <n>'
hosts and users by count and volume. The default is 50, and setting 0
suppresses the output altogether.


File: exim.info,  Node: -tnl,  Next: -ne,  Prev: -t<n>,  Up: Mail statistics

-tnl _option_
-------------

Omit local information from the `top' listings.


File: exim.info,  Node: -ne,  Prev: -tnl,  Up: Mail statistics

-ne _option_
------------

Suppress the list of delivery errors.


File: exim.info,  Node: Mailbox maintenance,  Next: Mailbox maintenance (continued),  Prev: Mail statistics,  Up: Exim utilities

Mailbox maintenance
===================

The "exim_lock" utility locks a mailbox file using the same algorithm
as Exim.  This can be used to prevent any modification of a mailbox by
Exim or a user agent while investigating a problem. The utility
requires the name of the file as its first argument. If the locking is
successful, the second argument is run as a command (using C's
"system()" function); if there is no second argument, the value of the
SHELL environment variable is used; if this is unset or empty,
"/bin/sh" is run. When the command finishes, the mailbox is unlocked
and the utility ends. The following options are available:



* Menu:

* -fcntl (exim_lock)::
* -interval (exim_lock)::
* -lockfile (exim_lock)::
* -mbx (exim_lock)::
* -retries (exim_lock)::
* -timeout (exim_lock)::
* -v (exim_lock)::
* -q (exim_lock)::


File: exim.info,  Node: -fcntl (exim_lock),  Next: -interval (exim_lock),  Prev: Mailbox maintenance,  Up: Mailbox maintenance

-fcntl (exim_lock) _option_
---------------------------

Use "fcntl()" locking on the open mailbox.


File: exim.info,  Node: -interval (exim_lock),  Next: -lockfile (exim_lock),  Prev: -fcntl (exim_lock),  Up: Mailbox maintenance

-interval (exim_lock) _option_
------------------------------

This must be followed by a number, which is a number of seconds; it
sets the interval to sleep between retries (default 3).


File: exim.info,  Node: -lockfile (exim_lock),  Next: -mbx (exim_lock),  Prev: -interval (exim_lock),  Up: Mailbox maintenance

-lockfile (exim_lock) _option_
------------------------------

Create a lock file before opening the mailbox.


File: exim.info,  Node: -mbx (exim_lock),  Next: -retries (exim_lock),  Prev: -lockfile (exim_lock),  Up: Mailbox maintenance

-mbx (exim_lock) _option_
-------------------------

Lock the mailbox using MBX rules.


File: exim.info,  Node: -retries (exim_lock),  Next: -timeout (exim_lock),  Prev: -mbx (exim_lock),  Up: Mailbox maintenance

-retries (exim_lock) _option_
-----------------------------

This must be followed by a number; it sets the number of times to try
to get the lock (default 10).


File: exim.info,  Node: -timeout (exim_lock),  Next: -v (exim_lock),  Prev: -retries (exim_lock),  Up: Mailbox maintenance

-timeout (exim_lock) _option_
-----------------------------

This must be followed by a number, which is a number of seconds; it
sets a timeout to be used with a blocking "fcntl()" lock. If it is not
set (the default), a non-blocking call is used.


File: exim.info,  Node: -v (exim_lock),  Next: -q (exim_lock),  Prev: -timeout (exim_lock),  Up: Mailbox maintenance

-v (exim_lock) _option_
-----------------------

Generate verbose output.


File: exim.info,  Node: -q (exim_lock),  Prev: -v (exim_lock),  Up: Mailbox maintenance

-q (exim_lock) _option_
-----------------------

Suppress verification output.


File: exim.info,  Node: Mailbox maintenance (continued),  Prev: Mailbox maintenance,  Up: Exim utilities

If none of -fcntl, -lockfile or -mbx are given, the default is to
create a lock file and also use "fcntl()" locking on the mailbox, which
is the same as Exim's default. The use of -fcntl requires that the file
be writeable; the use of -lockfile requires that the directory
containing the file be writeable. Locking by lock file does not last
for ever; Exim assumes that a lock file is expired if it is more than
30 minutes old.

The -mbx option is mutually exclusive with -fcntl. It causes a shared
lock to be taken out on the open mailbox, and an exclusive lock on the
file "/tmp/.n.m" where n and m are the device number and inode number
of the mailbox file. When the locking is released, if an exclusive lock
can be obtained for the mailbox, the file in "/tmp" is deleted.

The default output contains verification of the locking that takes
place. The -v option causes some additional information to be given.
The -q option suppresses all output except error messages.

A command such as

     exim_lock /var/spool/mail/spqr

runs an interactive shell while the file is locked, whereas

     exim_lock -q /var/spool/mail/spqr <<End
     <some commands>
     End

runs a specific non-interactive sequence of commands while the file is
locked, suppressing all verification output. A single command can be
run by a command such as

     exim_lock -q /var/spool/mail/spqr \
       "cp /var/spool/mail/spqr /some/where"

Note that if a command is supplied, it must be entirely contained
within the second argument - hence the quotes.


File: exim.info,  Node: The Exim monitor,  Next: Security considerations,  Prev: Exim utilities,  Up: Top

The Exim monitor
****************

The Exim monitor is an application which displays in an X window
information about the state of Exim's queue and what Exim is doing. An
admin user can perform certain operations on messages from this GUI
interface; however all such facilities are also available from the
command line, and indeed, the monitor itself makes use of it.



* Menu:

* Running the monitor::
* The stripcharts::
* Main action buttons::
* The log display::
* The queue display::
* The queue menu::


File: exim.info,  Node: Running the monitor,  Next: The stripcharts,  Prev: The Exim monitor,  Up: The Exim monitor

Running the monitor
===================

The monitor is started by running the script called "eximon". This is a
shell script which sets up a number of environment variables, and then
runs the binary called "eximon.bin". The appearance of the monitor
window can be changed by editing the "Local/eximon.conf" file created
by editing "exim_monitor/EDITME". Comments in that file describe what
the various parameters are for.

The parameters that get built into the "eximon" script can be
overridden for a particular invocation by setting up environment
variables of the same names, preceded by `EXIMON_'. For example, a
shell command such as

     EXIMON_LOG_DEPTH=400 eximon

(in a Bourne-compatible shell) runs "eximon" with an overriding setting
of the LOG_DEPTH parameter.  If EXIMON_LOG_FILE_PATH is set in the
environment, it overrides the Exim log file configuration. This makes
it possible to have "eximon" tailing log data that is written to
syslog, provided that MAIL.INFO syslog messages are routed to a file on
the local host.

X resources can be used to change the appearance of the window in the
normal way. For example, a resource setting of the form

     Eximon*background: gray94

changes the colour of the background to light grey rather than white.
The stripcharts are drawn with both the data lines and the reference
lines in black. This means that the reference lines are not visible
when on top of the data. However, their colour can be changed by
setting a resource called `highlight' (an odd name, but that's what the
Athena stripchart widget uses).  For example, if your X server is
running Unix, you could set up lighter reference lines in the
stripcharts by obeying

     xrdb -merge <<End
     Eximon*highlight: gray
     End

In order to see the contents of messages on the spool, and to operate
on them, "eximon" must either be run as root or by an admin user.

The monitor's window is divided into three parts. The first contains
one or more stripcharts and two action buttons, the second contains a
`tail' of the main log file, and the third is a display of the queue of
messages awaiting delivery, with two more action buttons. The following
sections describe these different displays.


File: exim.info,  Node: The stripcharts,  Next: Main action buttons,  Prev: Running the monitor,  Up: The Exim monitor

The stripcharts
===============

The first stripchart is always a count of messages on the queue.  Its
name can be configured by setting QUEUE_STRIPCHART_NAME in the
"Local/eximon.conf" file.  The remaining stripcharts are defined in the
configuration script by regular expression matches on log file entries,
making it possible to display, for example, counts of messages
delivered to certain hosts or using certain transports. The supplied
defaults display counts of received and delivered messages, and of
local and SMTP deliveries. The default period between stripchart
updates is one minute; this can be adjusted by a parameter in the
"Local/eximon.conf" file.

The stripchart displays rescale themselves automatically as the value
they are displaying changes. There are always 10 horizontal lines in
each chart; the title string indicates the value of each division when
it is greater than one.  For example, `x2' means that each division
represents a value of 2.

It is also possible to have a stripchart which shows the percentage
fullness of a particular disc partition, which is useful when local
deliveries are confined to a single partition.  This relies on the
availability of the "statvfs" function or equivalent in the operating
system. Most, but not all versions of Unix that support Exim have this.
For this particular stripchart, the top of the chart always represents
100%, and the scale is given as `x10%'. It is configured by setting
SIZE_STRIPCHART and (optionally) SIZE_STRIPCHART_NAME in the
"Local/eximon.conf" file.


File: exim.info,  Node: Main action buttons,  Next: The log display,  Prev: The stripcharts,  Up: The Exim monitor

Main action buttons
===================

Below the stripcharts there is an action button for quitting the
monitor. Next to this is another button marked `Size'. They are placed
here so that shrinking the window to its default minimum size leaves
just the queue count stripchart and these two buttons visible. Pressing
the `Size' button causes the window to expand to its maximum size,
unless it is already at the maximum, in which case it is reduced to its
minimum.

When expanding to the maximum, if the window cannot be fully seen where
it currently is, it is moved back to where it was the last time it was
at full size. When it is expanding from its minimum size, the old
position is remembered, and next time it is reduced to the minimum it
is moved back there.

The idea is that you can keep a reduced window just showing one or two
stripcharts at a convenient place on your screen, easily expand it to
show the full window when required, and just as easily put it back to
what it was.  The idea is copied from what the "twm" window manager
does for its "f.fullzoom" action. The minimum size of the window can be
changed by setting the MIN_HEIGHT and MIN_WIDTH values in
"Local/eximon.conf".

Normally, the monitor starts up with the window at its full size, but
it can be built so that it starts up with the window at its smallest
size, by setting START_SMALL=yes in "Local/eximon.conf".


File: exim.info,  Node: The log display,  Next: The queue display,  Prev: Main action buttons,  Up: The Exim monitor

The log display
===============

The second section of the window is an area in which a display of the
tail of the main log is maintained.  This is not available when the
only destination for logging data is syslog, unless the syslog lines
are routed to a local file whose name is passed to "eximon" via the
EXIMON_LOG_FILE_PATH environment variable.

The log sub-window has a scroll bar at its lefthand side which can be
used to move back to look at earlier text, and the up and down arrow
keys also have a scrolling effect. The amount of log that is kept
depends on the setting of LOG_BUFFER in "Local/eximon.conf", which
specifies the amount of memory to use. When this is full, the earlier
50% of data is discarded - this is much more efficient than throwing it
away line by line. The sub-window also has a horizontal scroll bar for
accessing the ends of long log lines. This is the only means of
horizontal scrolling; the right and left arrow keys are not available.
Text can be cut from this part of the window using the mouse in the
normal way.  The size of this subwindow is controlled by parameters in
the configuration file "Local/eximon.conf".

Searches of the text in the log window can be carried out by means of
the ^R and ^S keystrokes, which default to a reverse and forwards
search respectively.  The search covers only the text that is displayed
in the window. It cannot go further back up the log.

The point from which the search starts is indicated by a caret marker.
This is normally at the end of the text in the window, but can be
positioned explicitly by pointing and clicking with the left mouse
button, and is moved automatically by a successful search. If new text
arrives in the window when it is scrolled back, the caret remains where
it is, but if the window is not scrolled back, the caret is moved to
the end of the new text.

Pressing ^R or ^S pops up a window into which the search text can be
typed.  There are buttons for selecting forward or reverse searching,
for carrying out the search, and for cancelling. If the `Search' button
is pressed, the search happens and the window remains so that further
searches can be done. If the `Return' key is pressed, a single search
is done and the window is closed. If ^C is pressed the search is
cancelled.

The searching facility is implemented using the facilities of the
Athena text widget. By default this pops up a window containing both
`search' and `replace' options. In order to suppress the unwanted
`replace' portion for eximon, a modified version of the "TextPop"
widget is distributed with Exim. However, the linkers in BSDI and HP-UX
seem unable to handle an externally provided version of "TextPop" when
the remaining parts of the text widget come from the standard
libraries. The compile-time option EXIMON_TEXTPOP can be unset to cut
out the modified "TextPop", making it possible to build Eximon on these
systems, at the expense of having unwanted items in the search popup
window.


File: exim.info,  Node: The queue display,  Next: The queue menu,  Prev: The log display,  Up: The Exim monitor

The queue display
=================

The bottom section of the monitor window contains a list of all
messages that are on the queue, which includes those currently being
received or delivered, as well as those awaiting delivery. The size of
this subwindow is controlled by parameters in the configuration file
"Local/eximon.conf", and the frequency at which it is updated is
controlled by another parameter in the same file - the default is 5
minutes, since queue scans can be quite expensive.  However, there is
an `Update' action button just above the display which can be used to
force an update of the queue display at any time.

When a host is down for some time, a lot of pending mail can build up
for it, and this can make it hard to deal with other messages on the
queue. To help with this situation there is a button next to `Update'
called `Hide'. If pressed, a dialogue box called `Hide addresses ending
with' is put up. If you type anything in here and press `Return', the
text is added to a chain of such texts, and if every undelivered
address in a message matches at least one of the texts, the message is
not displayed.

If there is an address that does not match any of the texts, all the
addresses are displayed as normal. The matching happens on the ends of
addresses so, for example, "cam.ac.uk" specifies all addresses in
Cambridge, while "xxx@foo.com" specifies just one specific address.
When any hiding has been set up, a button called `Unhide' is displayed.
If pressed, it cancels all hiding. Also, to ensure that hidden messages
don't get forgotten, a hide request is automatically cancelled after
one hour.

While the dialogue box is displayed, you can't press any buttons or do
anything else to the monitor window. For this reason, if you want to
cut text from the queue display to use in the dialogue box, you have to
do the cutting before pressing the `Hide' button.

The queue display contains, for each unhidden queued message, the
length of time it has been on the queue, the size of the message, the
message id, the message sender, and the first undelivered recipient,
all on one line. If it is a delivery error message, the sender is shown
as `<>'. If there is more than one recipient to which the message has
not yet been delivered, subsequent ones are listed on additional lines,
up to a maximum configured number, following which an ellipsis is
displayed. Recipients that have already received the message are not
shown.  If a message is frozen, an asterisk is displayed at the
left-hand side.

The queue display has a vertical scroll bar, and can also be scrolled
by means of the arrow keys. Text can be cut from it using the mouse in
the normal way.  The text searching facilities, as described above for
the log window, are also available, but the caret is always moved to
the end of the text when the queue display is updated.


File: exim.info,  Node: The queue menu,  Prev: The queue display,  Up: The Exim monitor

The queue menu
==============

If the "shift" key is held down and the left button is clicked when the
mouse pointer is over the text for any message, an action menu pops up,
and the first line of the queue display for the message is highlighted.
This does not affect any selected text.  If you want to use some other
event for popping up the menu, you can set the MENU_EVENT parameter in
"Local/eximon.conf" to change the default, or set EXIMON_MENU_EVENT in
the environment before starting the monitor.  The value set in this
parameter is a standard X event description. For example, to run eximon
using "ctrl" rather than "shift" you could use

     EXIMON_MENU_EVENT='Ctrl<Btn1Down>' eximon

The title of the menu is the message id, and it contains entries which
act as follows:

   * "message log": The contents of the message log for the message are
     displayed in a new text window.

   * "headers": Information from the spool file that contains the
     envelope information and headers is displayed in a new text
     window. See chapter "Format of spool files" for a description of
     the format of spool files.

   * "body": The contents of the spool file containing the body of the
     message are displayed in a new text window.  There is a default
     limit of 20,000 bytes to the amount of data displayed. This can be
     changed by setting the BODY_MAX option at compile time, or the
     EXIMON_BODY_MAX option at run time.

   * "deliver message": A call to Exim is made using the -M option to
     request delivery of the message. This causes an automatic thaw if
     the message is frozen. The -v option is also set, and the output
     from Exim is displayed in a new text window. The delivery is run
     in a separate process, to avoid holding up the monitor while the
     delivery proceeds.

   * "freeze message": A call to Exim is made using the -Mf option to
     request that the message be frozen.

   * "thaw message": A call to Exim is made using the -Mt option to
     request that the message be thawed.

   * "give up on msg": A call to Exim is made using the -Mg option to
     request that Exim gives up trying to deliver the message. A
     delivery failure report is generated for any remaining undelivered
     addresses.

   * "remove message": A call to Exim is made using the -Mrm option to
     request that the message be deleted from the system without
     generating any failure reports.

   * "add recipient": A dialog box is displayed into which a recipient
     address can be typed. If the address is not qualified and the
     QUALIFY_DOMAIN parameter is set in "Local/eximon.conf", the
     address is qualified with that domain.  Otherwise it must be
     entered as a fully qualified address. Pressing RETURN causes a
     call to Exim to be made using the -Mar option to request that an
     additional recipient be added to the message, unless the entry box
     is empty, in which case no action is taken.

   * "mark delivered": A dialog box is displayed into which a recipient
     address can be typed. If the address is not qualified and the
     QUALIFY_DOMAIN parameter is set in "Local/eximon.conf", the
     address is qualified with that domain.  Otherwise it must be
     entered as a fully qualified address. Pressing RETURN causes a
     call to Exim to be made using the -Mmd option to mark the given
     recipient address as already delivered, unless the entry box is
     empty, in which case no action is taken.

   * "mark all delivered": A call to Exim is made using the -Mmad
     option to mark all recipient addresses as already delivered.

   * "edit sender": A dialog box is displayed initialized with the
     current sender's address. Pressing RETURN causes a call to Exim to
     be made using the -Mes option to replace the sender address,
     unless the entry box is empty, in which case no action is taken.
     If the address is not qualified and the QUALIFY_DOMAIN parameter
     is set in "Local/eximon.conf", the address is qualified with that
     domain. Otherwise it must be a fully qualified address.

   * "edit body": A new xterm process is forked in which a call to Exim
     is made using the -Meb option in order to allow the body of the
     message to be edited.  Note that the first line of the body file
     is the name of the file, and this should never be changed.

In cases when a call to Exim is made, the actual command used is
reflected in a new text window by default, but this can be turned off
for all except the delivery action by setting ACTION_OUTPUT=no in
"Local/eximon.conf".  However, if the call results in any output from
Exim (in particular, if the command fails) a window containing the
command and the output is displayed.  Otherwise, the results of the
action are normally apparent from the log and queue displays. The
latter is automatically updated for actions such as freezing and
thawing, unless ACTION_QUEUE_UPDATE=no has been set in
"Local/eximon.conf". In this case the `Update' button has to be used to
force an update to the display after freezing or thawing.

In any text window that is displayed as result of a menu action, the
normal cut-and-paste facility is available, and searching can be
carried out using ^R and ^S, as described above for the log tail window.


File: exim.info,  Node: Security considerations,  Next: Format of spool files,  Prev: The Exim monitor,  Up: Top

Security considerations
***********************

This chapter discusses a number of issues concerned with security, some
of which are also covered in other parts of this manual.

For reasons that this author does not understand, some people have
promoted Exim as a `particularly secure' mailer. Perhaps it is because
of the existence of this chapter in the documentation. However, the
intent of the chapter is simply to describe the way Exim works in
relation to certain security concerns, not to make any specific claims
about the effectiveness of its security as compared with other MTAs.

What follows is a description of the way Exim is supposed to be. Best
efforts have been made to try to ensure that the code agrees with the
theory, but an absence of bugs can never be guaranteed. Any that are
reported will get fixed as soon as possible.



* Menu:

* Root privilege::
* Running Exim without privilege::
* Alternate configurations and macros::
* Reading forward files::
* Delivering to local files::
* IPv4 source routing::
* The VRFY and EXPN and ETRN commands in SMTP::
* Privileged users::
* Spool files::
* Use of argv[0]::
* Use of %f formatting::
* Embedded Exim path::
* Use of sprintf()::
* Use of debug_printf() and log_write()::
* Use of strcat() and strcpy()::


File: exim.info,  Node: Root privilege,  Next: Running Exim without privilege,  Prev: Security considerations,  Up: Security considerations

Root privilege
==============

The Exim binary is normally setuid to root. In some special cases (for
example, when the daemon is not in use and there are no conventional
local deliveries), it may be possible to run it setuid to some user
other than root. However, root privilege is usually required for two
things:

   * To set up a socket connected to the standard SMTP port (25) when
     initialising the listening daemon.  If Exim is run from "inetd",
     this privileged action is not required.

   * To be able to change uid and gid in order to read forward files
     and perform local deliveries as the receiving user or as specified
     in the configuration.

It is not necessary to be root to do any of the other things Exim does,
such as receiving messages and delivering them externally over SMTP,
and it is obviously more secure if Exim does not run as root except
when necessary.

If no user is specified for Exim in either the compile-time or run time
configuration files, it runs as root all the time, except when
performing local deliveries. When an alternative user is specified
(which is recommended), it gives up root privilege when it can. Exactly
how and when it does this depends on whether the operating system
supports the "seteuid()" or the "setresuid()" function.

To avoid unnecessary complication, the discussion below talks about
users, and functions for setting the uid. It should be understood that
in all cases there is a corresponding group and gid, and that this is
also changed whenever the uid is changed.  The description is written
in terms of "seteuid()", since this is more common than "setresuid()".
However, it is possible to specify at compile time that an operating
system has "setresuid()" and not "seteuid()".

On systems without "seteuid()", Exim uses "setuid()" to give up root
privilege at certain times, at the expense of having to re-invoke
itself (using "exec") in order to regain privilege when necessary. If
"seteuid()" is available, there is a configuration choice as to which
method is used for temporarily giving up the privilege. Using
"setuid()" is more secure, and is the default, but uses more resources.

There are two instances in which Exim always uses "setuid()":

   * Exim always uses "setuid()" to become a non-root user when running
     a local delivery process. There are no exceptions. This applies
     whether or not an Exim user is defined.

   * Exim always uses "setuid()" to change to the Exim user (if one is
     defined) before doing remote deliveries. These are the last things
     a delivery process does, so it does not need to regain root
     privilege again.

There are two instances in which Exim always uses "seteuid()" (provided
it is available in the operating system):

   * When reading a user's `.forward' file, Exim uses "seteuid()" to
     become that user. This is necessary when the file is not publicly
     readable and is on a remote NFS file system that is mounted
     without root privilege. If this is the case on a system without
     "seteuid()", the `.forward' file cannot be read.

   * If any director or router has the "require_files" option set to
     check the existence of a file as a specific user, "seteuid()" is
     used to become that user for the duration of the check.

For other operations, the "security" configuration option controls
whether Exim uses "setuid()" or "seteuid()" to change to its own uid.
It can be set to one of three strings:

   * "seteuid": Exim uses "seteuid()" to give up root temporarily when
     it does not need it, and to regain the privilege subsequently.
     This enables it to run with a non-root effective uid most of the
     time, at very little cost, but offers less security.

   * "setuid": Exim uses "setuid()" to give up root when it is
     receiving a locally generated message, and after it has set up a
     listening socket when running as a daemon. This means that, in
     order to deliver a message that it has received, it has to
     re-invoke a fresh copy of itself to regain root privilege. During
     delivery, it retains root except when actually transporting the
     message. In particular, it runs the directors and routers as root.
     "Setuid()" is generally reckoned to be more secure than
     "seteuid()" but running this way uses more resources.

   * "setuid+seteuid": Exim uses "setuid()" as described immediately
     above, but in addition, it uses "seteuid()" to give up root
     privilege temporarily when it needs to regain it subsequently
     without losing a lot of state information, for example, while
     running the directors and routers.

On systems that do not support the "seteuid()" function, the only
possible value for the "security" option is `setuid', and this is the
default on such systems if an Exim user is defined. Otherwise the
default is `setuid+seteuid' - the most secure setting.


File: exim.info,  Node: Running Exim without privilege,  Next: Alternate configurations and macros,  Prev: Root privilege,  Up: Security considerations

Running Exim without privilege
==============================

Some installations require to run Exim in an unprivileged state almost
all the time, for added security. Support for this mode of operation is
provided by the setting

     security = unprivileged

When this is done, all deliveries take place under the Exim user/group
(which must be defined), and there are restrictions on the features
that can be used in the configuration. There are two possibilities if
you want to run Exim in this way:

   * Keep it setuid to "root", as in standard configurations. In this
     configuration, except when starting the daemon, Exim gives up the
     root privilege and becomes the Exim user/group as soon as it has
     started, using "setuid()" and "setgid()".  This removes all
     privilege that might have been associated with the calling user.
     In the case of the daemon, root privilege is retained until it has
     bound its listening socket to the SMTP port, but then it gives it
     up in the same way.  The daemon can respond correctly to SIGHUP
     because the re-invocation regains root privilege.

   * Make Exim setuid/setgid to the Exim user and group. This means it
     cannot start up the daemon unless it is called by a root process,
     and consequently, the daemon cannot restart itself as a result of
     SIGHUP because it is no longer a root process at that point. It is
     still useful to set

          security = unprivileged

     in this case, because this setting stops Exim from trying to
     re-invoke itself to do a delivery after a message has been
     received. Such a re-invocation is a waste of time because it would
     have no effect.

When using the second style (setuid to the Exim user), unless called by
root (in which case it behaves as in the first style), Exim is running
with the real uid and gid set to those of the calling process, and the
effective uid/gid set to Exim's values. Ideally, any association with
the calling process' uid/gid should be dropped, that is, the real
uid/gid should be reset to the effective values so as to discard any
privileges that the caller may have. While some operating systems have
a function that permits this action for a non-root effective uid, quite
a number of them do not. Because of this lack of standardization, Exim
does not address this problem at this time. For this reason, the first
style is perhaps the better approach to take.

Because Exim no longer needs to re-exec itself when starting a delivery
process after receiving a message, using

     security = unprivileged

is more efficient than either of

     security = setuid
     security = setuid+seteuid

However, to achieve this extra efficiency you have to submit to the
following restrictions:

You can deliver only as the Exim user/group. You should  explicitly use
the "user" and "group" options to override directors or transports that
normally deliver as the recipient. (This makes sure that configurations
that work in this mode function the same way in normal mode.) Any
implicit or explicit specification of another user causes an error.

Use of `.forward' files is severely restricted, such that it is usually
not worthwhile to include a "forwardfile" director in the configuration.

Users who wish to use `.forward' would have to make their home
directory and the file itself accessable to the Exim user. Pipe and
append-to-file entries, and their equivalents in Exim filters, cannot
be used. While they could be enabled in the Exim user's name, that
would be insecure and not very useful.

Unless the user mailboxes are all owned by the Exim user (possible in
some POP3 or IMAP-only environments):

   * They must be owned by the Exim group and be writable by that group.
     This implies you must set "mode" in the appendfile configuration,
     as well as the mode of the mailbox files themselves.

   * You must set "no_check_owner", since most or all of the files will
     not be owned by the Exim user.

   * You must set "file_must_exist", as Exim cannot set the owner
     correctly on a newly created mailbox when unpriviledged. This also
     implies that new mailboxes need to be created manually.

There are no additional restrictions on message reception or external
(SMTP) delivery.


File: exim.info,  Node: Alternate configurations and macros,  Next: Reading forward files,  Prev: Running Exim without privilege,  Up: Security considerations

Alternate configurations and macros
===================================

Exim can be run with an alternate configuration file by means of the -C
option, and macros for use in its configuration can be set on the
command line using the -D option. If the -C option specifies a file
other than the one whose name is built into the binary, or if there is
any use of the -D option, and the caller is not root or the Exim user,
Exim immediately gives up its privilege, and runs with the real and
effective uid and gid set to those of the caller.


File: exim.info,  Node: Reading forward files,  Next: Delivering to local files,  Prev: Alternate configurations and macros,  Up: Security considerations

Reading forward files
=====================

When forward files are read from users' home directories and those home
directories are NFS mounted without root privilege, even a program
running as root cannot read a forward file that does not have world
read access.

If the "seteuid()" function is being used as described in the previous
section, so that Exim is not root when running the directors, the
"forwardfile" director automatically uses "seteuid()" to become the
local user when attempting to read a `.forward' file in a user's home
directory. If "seteuid()" is not being used generally, but is available
in the operating system, the "forwardfile" director can be configured
to make use of it when reading files in home directories.

The "forwardfile" director does not necessarily have to read from
users' home directories as obtained from "getpwnam()". It can be given
a directory explicitly, and a specific associated user and group. The
above remarks are applicable in this case also.

On systems that do not have "seteuid()", the only way to support
forward files on NFS file systems that do not export root is to insist
that the files be world readable.

Forward files are permitted to contain :include: items unless forbidden
by setting "forbid_include" in the director. If "seteuid()" is being
used to read the forward file, any included files are read as the same
user. Otherwise Exim is running as root, and it insists that any
included files are within the same directory as the forward file, and
that there are no symbolic links below the directory. If no directory
is specified (either explicitly or by looking up a local user's home
directory) then included files are not permitted when "seteuid()" is
not in use.

When the filtering option is enabled for forward files, users can
construct pipe commands that contain data from the incoming message by
quoting variables such as $sender_address. To prevent the contents of
inserted data from interfering with a command, the string expansion is
done after the command line is split up into separate arguments, and
the command is run directly instead of passing the command line to a
shell.


File: exim.info,  Node: Delivering to local files,  Next: IPv4 source routing,  Prev: Reading forward files,  Up: Security considerations

Delivering to local files
=========================

Full details of the checks applied by "appendfile" before it writes to
a file are given in chapter "The appendfile transport".


File: exim.info,  Node: IPv4 source routing,  Next: The VRFY and EXPN and ETRN commands in SMTP,  Prev: Delivering to local files,  Up: Security considerations

IPv4 source routing
===================

Many operating systems suppress IP source-routed packets in the kernel,
but some cannot be made to do this. Exim is configured by default to
log incoming IPv4 source-routed TCP calls, and then to drop the call.
These actions can be independently turned off. Alternatively, the IP
options can be deleted instead of dropping the call. Things are all
different in IPv6. No special checking is currently done.


File: exim.info,  Node: The VRFY and EXPN and ETRN commands in SMTP,  Next: Privileged users,  Prev: IPv4 source routing,  Up: Security considerations

The VRFY, EXPN, and ETRN commands in SMTP
=========================================

Support for these SMTP commands is disabled by default. The VRFY command
can be enabled by setting "smtp_verify". The EXPN command can be enabled
for specific hosts by setting "smtp_expn_hosts", and there is a similar
option controlling ETRN.


File: exim.info,  Node: Privileged users,  Next: Spool files,  Prev: The VRFY and EXPN and ETRN commands in SMTP,  Up: Security considerations

Privileged users
================

Exim recognises two sets of users with special privileges. Trusted
users are able to submit new messages to Exim locally, but supply their
own sender addresses and information about a sending host. For other
users submitting local messages, Exim sets up the sender address from
the uid, and doesn't permit a remote host to be specified.

However, an untrusted user is permitted to use the -f command line
option in the special form -f <> to indicate that a delivery failure
for the message should not cause an error report. This affects the
message's envelope, but it does not affect the "Sender:" header.

Trusted users are used to run processes that receive mail messages from
some other mail domain and pass them on to Exim for delivery either
locally, or over the Internet. Exim trusts a caller that is running as
root, as the Exim user (if defined), as any user listed in the
"trusted_users" configuration option, or under any group listed in the
"trusted_groups" option.

Admin users are permitted to do things to the messages on Exim's queue.
They can freeze or thaw messages, cause them to be returned to their
senders, remove them entirely, or modify them in various ways. In
addition, admin users can run the Exim monitor and see all the
information it is capable of providing, which includes the contents of
files on the spool.

By default, the use of the -M and -q options to cause Exim to attempt
delivery of messages on its queue is restricted to admin users.
However, this restriction can be relaxed by setting the
"no_prod_requires_admin" option.

Exim recognises an admin user if the calling process is running as root
or as the Exim user (if defined) or if any of the groups associated
with the calling process is the Exim group (if defined). It is not
necessary actually to be running under the Exim group. However, if
admin users who are not root or exim are to access the contents of
files on the spool via the Exim monitor (which runs unprivileged), Exim
must be built to allow group read access to its spool files.


File: exim.info,  Node: Spool files,  Next: Use of argv[0],  Prev: Privileged users,  Up: Security considerations

Spool files
===========

If a uid and gid are defined for Exim, the spool directory and
everything it contains will be owned by exim and have its group set to
exim. The mode for spool files is defined in the `Local/Makefile'
configuration file, and defaults to 0600. This should normally be
changed to 0640 if a uid and gid are defined for Exim, to allow access
to spool files via the Exim monitor by other members of the exim group.


File: exim.info,  Node: Use of argv[0],  Next: Use of %f formatting,  Prev: Spool files,  Up: Security considerations

Use of argv[0]
==============

Exim examines the last component of "argv[0]", and if it matches one of
a set of specific strings, Exim assumes certain options. For example,
calling Exim with the last component of "argv[0]" set to `rsmtp' is
exactly equivalent to calling it with the option -bS. There are no
security implications in this.


File: exim.info,  Node: Use of %f formatting,  Next: Embedded Exim path,  Prev: Use of argv[0],  Up: Security considerations

Use of %f formatting
====================

The only use made of `%f' by Exim is in formatting load average values.
These are actually stored in integer variables as 1000 times the load
average.  Consequently, their range is limited and so therefore is the
length of the converted output.


File: exim.info,  Node: Embedded Exim path,  Next: Use of sprintf(),  Prev: Use of %f formatting,  Up: Security considerations

Embedded Exim path
==================

Exim uses its own path name, which is embedded in the code, only when
it needs to re-exec in order to regain root privilege. Therefore it is
not root when it does so. If some bug allowed the path to get
overwritten, it would lead to an arbitrary program's being run as exim,
not as root. If there's still paranoia about this, two separate copies
of the name could be kept, or a checksum could be applied to the global
data.


File: exim.info,  Node: Use of sprintf(),  Next: Use of debug_printf() and log_write(),  Prev: Embedded Exim path,  Up: Security considerations

Use of sprintf()
================

A large number of occurrences of `sprintf' in the code are actually
calls to "string_sprintf()", a function which returns the result in
malloc'd store. The intermediate formatting is done into a large fixed
buffer by a function that runs through the format string itself, and
checks the length of each conversion before performing it, thus
preventing buffer overruns.

The remaining uses of "sprintf()" happen in controlled circumstances
where the output buffer is known to be sufficiently long to contain the
converted string.


File: exim.info,  Node: Use of debug_printf() and log_write(),  Next: Use of strcat() and strcpy(),  Prev: Use of sprintf(),  Up: Security considerations

Use of debug_printf() and log_write()
=====================================

Arbitrary strings are passed to both these functions, but they do their
formatting by calling the function "string_vformat()", which runs
through the format string itself, and checks the length of each
conversion.


File: exim.info,  Node: Use of strcat() and strcpy(),  Prev: Use of debug_printf() and log_write(),  Up: Security considerations

Use of strcat() and strcpy()
============================

These are used only in cases where the output buffer is known to be
large enough to hold the result.


File: exim.info,  Node: Format of spool files,  Next: Adding new drivers or lookup types,  Prev: Security considerations,  Up: Top

Format of spool files
*********************

A message on Exim's spool consists of two files, whose names are the
message id followed by -D and -H, respectively. The data portion of the
message is kept in the -D file on its own. The message's `envelope',
status, and headers are all kept in the -H file, whose format is
described in this chapter. Each of these two files contains the final
component of its own name as its first line. This is insurance against
disc crashes where the directory is lost but the files themselves are
recoverable.

Files whose names end with -J may also be seen in the spool directory.
These are journal files, used to record addresses to which the message
has been delivered during the course of a delivery run. At the end of
the run, the -H file is updated, and the -J file is deleted.

The second line of the header file contains the login id of the process
that called Exim to create the file, followed by the numerical uid and
gid. For a locally generated message, this is normally the user who
sent the message. For an external message, the user is either root or
exim.

The third line of the file contains the address of the message's sender
as transmitted in the `envelope', contained in angle brackets. In the
case of incoming SMTP mail, this is the address given in the MAIL
command. For locally generated mail, the sender address is created by
Exim from the login of the current user and the configured
"qualify_domain", except when Exim is called by a trusted user that
supplied a sender address via the -f option, or a leading `From' line.
The sender address is null if the message is a delivery failure report.

The fourth line contains two numbers. The first is the time that the
message was received, in the form supplied by the Unix "time()"
function - a number of seconds since the start of the epoch. The second
number is a count of the number of messages warning of delayed delivery
that have been sent to the sender.

There follow a number of lines starting with a hyphen. These can appear
in any order, and are omitted when not relevant.

   * -auth_id <text>: The id information for a message received on an
     authenticated SMTP connection - the value of the $authenticated_id
     variable.

   * -auth_sender <address>: The address of an authenticated sender -
     the value of the $authenticated_sender variable.

   * -body_linecount <number>: This records the number of lines in the
     body of the message, and is always present.

   * -deliver_firsttime: This is written when a new message is first
     added to the spool. When the spool file is updated after a
     deferral, it is omitted.

   * -frozen <time>: The message is frozen, and the freezing happened at
     <time>. No deliveries will be attempted while the message remains
     frozen, but the "auto_thaw" configuration option can specify a
     time delay after which a delivery will be attempted.

   * -helo_name <text>: This records the host name as specified by a
     remote host in a HELO or EHLO command.

   * -host_auth <text>: If the message was received on an authenticated
     SMTP connection, this records the name of the authenticator - the
     value of the $sender_host_authenticated variable.

   * -host_lookup_failed: This is present if an attempt to look up the
     sending host's name from its IP address failed. It corresponds to
     the $host_lookup_failed variable.

   * -host_name <text>: This records the name of the remote host from
     which the message was received, if the host name was looked up
     from the IP address. It is not present if no reverse lookup was
     done.

   * -host_address <address>.<port>: This records the IP address of the
     remote host from which the message was received and the remote
     port number that was used. It is omitted for locally generated
     messages.

   * -ident <text>: For locally submitted messages, this records the
     login of the originating user, unless it was a trusted user and
     the -oMt option was used to specify an ident value. For messages
     received over TCP/IP, this records the ident string supplied by
     the remote host.

   * -interface_address <address>: This records the IP address of the
     local interface through which a message was received from a remote
     host. It is omitted for locally generated messages.

   * -local: The message is from a local sender.

   * -localerror: The message is a locally-generated delivery error
     report.

   * -manual_thaw: The message was frozen but has been thawed manually,
     that is, by an explicit Exim command rather than via the auto-thaw
     process.

   * -N: A testing delivery process was started using the -N option to
     suppress any actual deliveries, but delivery was deferred. At the
     next delivery attempt, -N is assumed.

   * -received_protocol: This records the value of the
     $received_protocol variable, which contains the name of the
     protocol by which the message was received.

   * -resent: The message contains `Resent-' headers, so the
     alternative set of header names is to be used (see RFC 822).

   * -sender_set_untrusted: The envelope sender of this message was set
     by an untrusted local caller (used to ensure that the caller is
     displayed in queue listings).

   * -tls_cipher <cipher name>: When the message was received over an
     encrypted channel, this records the name of the cipher that was
     used.

   * -tls_peerdn <peer DN>: When the message was received over an
     encrypted channel, and a certificate was requested from the
     client, this records the Distinguished Name from that certificate.

   * -user_null_sender: The message was received from an unprivileged
     user with the -f option specifying `<>' as the sender.

Following the options are those addresses to which the message is not
to be delivered. This set of addresses is initialized from the command
line when the -t option is used and
"extract_addresses_remove_arguments" is set; otherwise it starts out
empty. Whenever a successful delivery is made, the address is added to
this set. The addresses are kept internally as a balanced binary tree,
and it is a representation of that tree which is written to the spool
file. If an address is expanded via an alias or forward file, the
original address is added to the tree when deliveries to all its child
addresses are completed.

If the tree is empty, there is a single line in the spool file
containing just the text `XX'. Otherwise, each line consists of two
letters, which are either Y or N, followed by an address. The address
is the value for the node of the tree, and the letters indicate whether
the node has a left branch and/or a right branch attached to it,
respectively. If branches exist, they immediately follow. Here is an
example of a three-node tree:

     YY darcy@austen.fict.book
     NN alice@wonderland.fict.book
     NN editor@thesaurus.ref.book

After the non-recipients tree, there is a list of the message's
recipients.  This is a simple list, preceded by a count. It includes
all the original recipients of the message, including those to whom the
message has already been delivered.  In the simplest case, the list
contains one address per line.  For example:

     4
     editor@thesaurus.ref.book
     darcy@austen.fict.book
     rdo@foundation
     alice@wonderland.fict.book

However, when a child address has been added to the top-level addresses
as a result of the use of the "one_time" option on an "aliasfile" or
"forwardfile" director, each line is of the following form:

     <top-level address> <flags number>,<parent number>,0

The flags at present contain only one bit, which is set for "one_time"
addresses. It indicates that <parent number> is the offset in the
recipients list of the original parent of the address. The third number
of the trio is for future expansion and is currently always zero.  A
blank line separates the envelope and status information from the
headers which follow. A header may occupy several lines of the file,
and to save effort when reading it in, each header is preceded by a
number and an identifying character. The number is the number of
characters in the header, including any embedded newlines and the
terminating newline. The character is one of the following:

     <blank>   header in which Exim has no special interest
      B        "Bcc:" header
      C        "Cc:" header
      F        "From:" header
      I        "Message-id:" header
      P        "Received:" header -- P for `postmark'
      R        "Reply-To:" header
      S        "Sender:" header
      T        "To:" header
      *        replaced or deleted header

Deleted or replaced (rewritten) headers remain in the spool file for
debugging purposes. They are not transmitted when the message is
delivered. When `Resent-' headers are present, it is those headers that
have the appropriate flags. Here is a typical set of headers:

     111P Received: by hobbit.fict.book with local (Exim 3.30 #4)
             id 14y9EI-00026G-00; Fri, 11 May 2001 10:28:59 +0100
     049  Message-Id: <E14y9EI-00026G-00@hobbit.fict.book>
     038* X-rewrote-sender: bb@hobbit.fict.book
     042* From: Bilbo Baggins <bb@hobbit.fict.book>
     049F From: Bilbo Baggins <B.Baggins@hobbit.fict.book>
     099* To: alice@wonderland.fict.book, rdo@foundation,
      darcy@austen.fict.book, editor@thesaurus.ref.book
     109T To: alice@wonderland.fict.book, rdo@foundation.fict.book,
      darcy@austen.fict.book, editor@thesaurus.ref.book
     038  Date: Fri, 11 May 2001 10:28:59 +0100

The asterisked headers indicate that the envelope sender, "From:"
header, and "To:" header have been rewritten, the last one because
routing expanded the unqualified domain "foundation".


File: exim.info,  Node: Adding new drivers or lookup types,  Next: Concept Index,  Prev: Format of spool files,  Up: Top

Adding new drivers or lookup types
**********************************

The following actions have to be taken in order to add a new director,
router, transport, authenticator, or lookup type to Exim:

  1. Choose a name for the driver or lookup type that does not conflict
     with any existing name; I will use `newdriver' in what follows.

  2. Add to `src/EDITME' the line

          <type>_NEWDRIVER=yes

     where <type> is DIRECTOR, ROUTER, TRANSPORT, AUTH, or LOOKUP. If
     the code is not to be included in the binary by default, comment
     this line out. You should also add any relevant comments about the
     driver or lookup type.

  3. Add to "src/config.h.defaults" the line

          #define <type>_NEWDRIVER

  4. Edit "src/drtables.c", adding conditional code to pull in the
     private header and create a table entry as is done for all the
     other drivers and lookup types.

  5. Edit "Makefile" in the appropriate sub-directory ("src/directors",
     "src/routers", "src/transports", "src/auths", or "src/lookups");
     add a line for the new driver or lookup type and add it to the
     definition of OBJ.

  6. Create "newdriver.h" and "newdriver.c" in the appropriate
     sub-directory of "src".

  7. Edit "scripts/MakeLinks" and add commands to link the ".h" and
     ".c" files as for other drivers and lookups.

Then all you need to do is write the code! A good way to start is to
make a proforma by copying an existing module of the same type,
globally changing all occurrences of the name, and cutting out most of
the code. Note that any options you create must be listed in
alphabetical order, because the tables are searched using a binary chop
procedure.

There is a "README" file in each of the sub-directories of "src"
describing the interface that is expected.


File: exim.info,  Node: Concept Index,  Prev: Adding new drivers or lookup types,  Up: Top

Concept Index
*************

* Menu:

* $key <1>:                              domains (director or router).
* $key <2>:                              Expansion variables.
* $key <3>:                              Domain lists.
* $key <4>:                              local_parts (director or router).
* $key:                                  Use of data lookups.
* $value <1>:                            Expansion variables.
* $value <2>:                            Expansion items.
* $value:                                Host list format.
* *@:                                    Default values in single-key lookups.
* +allow_unknown:                        Host lists.
* +caseful:                              Case of letters in address lists.
* +warn_unknown:                         Host lists.
* /dev/null <1>:                         Types of alias item.
* /dev/null:                             Forward file items.
* /etc/passwd:                           Specifying a transport for aliasfile.
* 8-bit characters <1>:                  print_topbitchars.
* 8-bit characters <2>:                  accept_8bitmime.
* 8-bit characters:                      -B<type>.
* 8BITMIME:                              accept_8bitmime.
* `From' <1>:                            The UUCP From line.
* `From' <2>:                            ignore_fromline_hosts.
* `From' <3>:                            uucp_from_pattern.
* `From' <4>:                            -bm.
* `From':                                check_string (appendfile).
* `percent hack' <1>:                    percent_hack_domains.
* `percent hack' <2>:                    Other policy controls on incoming mail.
* `percent hack':                        Control of relaying.
* `sticky' bit <1>:                      file (appendfile).
* `sticky' bit:                          Testing.
* abandoning mail <1>:                   -Mrm <message id> <message id>.
* abandoning mail:                       Types of alias item.
* adding drivers:                        Adding new drivers or lookup types.
* additional groups <1>:                 group (lmtp).
* additional groups <2>:                 headers_remove (director or router).
* additional groups <3>:                 headers (autoreply).
* additional groups:                     ignore_status (pipe).
* address list case forcing:             Case of letters in address lists.
* address list format:                   Address lists.
* address: constructed:                  Constructed addresses.
* address: duplicated:                   Duplicate addresses.
* address: qualification:                Unqualified addresses.
* address: rewriting <1>:                Address rewriting.
* address: rewriting:                    Rewriting addresses.
* address: sender:                       -f <address>.
* address: source-routed <1>:            percent_hack_domains.
* address: source-routed:                collapse_source_routes.
* address: testing <1>:                  expn (director).
* address: testing:                      -bt.
* address: verification <1>:             Sender verification.
* address: verification:                 -bv.
* admin user <1>:                        Running the monitor.
* admin user <2>:                        admin_groups.
* admin user <3>:                        -Mar <message id> <address> <address>.
* admin user <4>:                        -Mf <message id> <message id>.
* admin user <5>:                        -Mg <message id> <message id>.
* admin user <6>:                        Privileged users.
* admin user <7>:                        -Mrm <message id> <message id>.
* admin user <8>:                        -Mt <message id> <message id>.
* admin user:                            Trusted and admin users.
* alias errors:                          Errors in alias files.
* alias file: <1>:                       Options common to the aliasfile and forwardfile directors.
* alias file::                           The aliasfile director.
* alias file: backslash in:              Types of alias item.
* alias file: building <1>:              -bi.
* alias file: building:                  Setting options by program name.
* alias file: defaults:                  Alias file format.
* alias file: multi-domain:              include_domain (aliasfile).
* alias file: one-time expansion:        one_time.
* alias file: ownership:                 owners.
* alias file: per-domain default:        Default values in single-key lookups.
* alias file: repeated expansion:        Repeated alias expansion.
* alias files: broken:                   skip_syntax_errors.
* alias for host:                        Host lists.
* aliasfile director <1>:                Current and home directories.
* aliasfile director <2>:                Uids and gids.
* aliasfile director <3>:                Options common to the aliasfile and forwardfile directors.
* aliasfile director:                    The aliasfile director.
* alternate configuration file <1>:      The Exim configuration file.
* alternate configuration file:          -C <filename>.
* angle brackets, excess:                strip_excess_angle_brackets.
* appendfile transport <1>:              Current and home directories.
* appendfile transport:                  The appendfile transport.
* appending to a file:                   Operational details for appending.
* architecture type:                     Overriding build-time options for Exim.
* arguments, logging:                    log_arguments.
* asterisk after IP address:             Outgoing SMTP over TCP/IP.
* Athena:                                Incorporated code.
* authentication: <1>:                   SMTP authentication.
* authentication: <2>:                   allow_localhost (smtp).
* authentication::                       -oMai <string>.
* authentication: advertising:           auth_always_advertise.
* authentication: client:                Authentication by an Exim client.
* authentication: generic options:       Generic options for authenticators.
* authentication: id:                    Expansion variables.
* authentication: relaying:              Authentication on an Exim server.
* authentication: sender <1>:            Expansion variables.
* authentication: sender <2>:            Authenticated senders.
* authentication: sender:                -oMas <address>.
* authentication: server:                Authentication on an Exim server.
* authentication: testing:               Testing server authentication.
* auto_thaw:                             Life of a message.
* automatic mail processing:             Automatic mail processing.
* autoreply transport <1>:               message_filter_reply_transport.
* autoreply transport:                   The autoreply transport.
* background delivery:                   -odb.
* backlog of connections:                smtp_connect_backlog.
* backslash in alias file:               Types of alias item.
* backslash in forward file:             Forward file items.
* bad senders (fixing):                  Fixing bad senders.
* bang paths::                           Limitations.
* bang paths: rewriting:                 Rewriting examples.
* banner for SMTP:                       smtp_banner.
* batch delivery <1>:                    batch (pipe).
* batch delivery:                        batch (lmtp).
* batched SMTP input <1>:                -bS.
* batched SMTP input <2>:                Sender verification.
* batched SMTP input:                    Incoming batched SMTP.
* batched SMTP output <1>:               Outgoing batched SMTP.
* batched SMTP output:                   Domainlist examples.
* Bcc: header <1>:                       always_bcc.
* Bcc: header <2>:                       The Bcc header.
* Bcc: header:                           -t.
* bcopy:                                 Limitations.
* Berkeley DB:                           DBM libraries.
* BIN_DIRECTORY:                         Installing commands and scripts.
* bind IP address <1>:                   hosts_randomize (smtp).
* bind IP address:                       local_interfaces.
* bitnet:                                Domainlist examples.
* black hole:                            Types of alias item.
* body of message: editing:              -Meb <message id>.
* body of message: expansion variable:   Expansion variables.
* body of message: line count:           Expansion variables.
* body of message: size:                 Expansion variables.
* body of message: transporting:         body_only (transport).
* body of message: visible size:         message_body_visible.
* broken alias or forward files:         skip_syntax_errors.
* build directory:                       The building process.
* building DBM files:                    Making DBM files.
* building Exim:                         Building and installing Exim.
* C header files:                        OS-specific header files.
* caching lookup data:                   Lookup caching.
* callback for verification <1>:         Sender verification with callback.
* callback for verification:             sender_verify_batch.
* carriage return <1>:                   use_crlf (appendfile).
* carriage return <2>:                   use_crlf (pipe).
* carriage return <3>:                   Incoming SMTP messages over TCP/IP.
* carriage return <4>:                   -dropcr.
* carriage return:                       Outgoing SMTP over TCP/IP.
* case forcing in address lists:         Case of letters in address lists.
* case forcing in strings:               Expansion operators.
* case of local parts <1>:               Case of letters in address lists.
* case of local parts:                   Case of local parts.
* cc compiler:                           Overriding build-time options for Exim.
* Cc: header <1>:                        always_bcc.
* Cc: header:                            -t.
* cdb <1>:                               Single-key lookup types.
* cdb <2>:                               Incorporated code.
* cdb:                                   Overriding build-time options for Exim.
* certificate::                          Certificates and all that.
* certificate: verifying:                Configuring Exim to use TLS as a server.
* character code:                        print_topbitchars.
* checking disc space <1>:               smtp_check_spool_space.
* checking disc space:                   check_spool_space.
* cipher: logging <1>:                   Configuring Exim to use TLS as a server.
* cipher: logging:                       Configuring Exim to use TLS as a client.
* cipher: verifying:                     Configuring Exim to use TLS as a server.
* closed mailing lists:                  senders (director or router).
* command line options:                  The Exim command line.
* common option syntax:                  Common option syntax.
* compiler name:                         Overriding build-time options for Exim.
* configuration file: alternate:         The Exim configuration file.
* configuration file: common option syntax: Common option syntax.
* configuration file: editing:           Overriding build-time options for Exim.
* configuration file: errors:            The Exim configuration file.
* configuration file: format:            Configuration file format.
* configuration file: macros:            Macros in the configuration file.
* configuration file: ownership:         The Exim configuration file.
* configuration options:                 -bP.
* configuration: changes:                Changing the configuration.
* configuration: default:                The default configuration file.
* configuration: main:                   Main configuration.
* configuration: pre-building:           Pre-building configuration.
* configuration: retry:                  Retry configuration.
* configuration: run time <1>:           The Exim configuration file.
* configuration: run time:               -C <filename>.
* CONFIGURE_FILE <1>:                    The Exim configuration file.
* CONFIGURE_FILE <2>:                    -C <filename>.
* CONFIGURE_FILE:                        Installing commands and scripts.
* connection backlog:                    smtp_connect_backlog.
* constructed address:                   Constructed addresses.
* control of incoming mail:              Other policy controls on incoming mail.
* control of relaying:                   Control of relaying.
* copy of message (unseen option):       unseen (director or router).
* Courier:                               Single-key lookup types.
* CR <1>:                                use_crlf (appendfile).
* CR <2>:                                -dropcr.
* CR <3>:                                Outgoing SMTP over TCP/IP.
* CR <4>:                                Incoming SMTP messages over TCP/IP.
* CR:                                    use_crlf (pipe).
* cram_md5 authenticator:                The cram_md5 authenticator.
* creating directories:                  The appendfile transport.
* current directory <1>:                 Current and home directories.
* current directory:                     Special treatment of home_directory and current_directory.
* current_directory:                     Special treatment of home_directory and current_directory.
* customizing: Received: header:         rbl_warn_header.
* customizing: SMTP banner:              smtp_banner.
* customizing: SMTP error messages:      Customizing prohibition messages.
* cycling logs:                          Cycling log files.
* Cyrus <1>:                             prefix (pipe).
* Cyrus:                                 Using an external local delivery agent.
* daemon <1>:                            -bd.
* daemon <2>:                            Changing the configuration.
* daemon <3>:                            local_interfaces.
* daemon:                                Incoming SMTP messages over TCP/IP.
* daemon, process id <1>:                -oX <number>.
* daemon, process id <2>:                -q <time>.
* daemon, process id <3>:                Changing the configuration.
* daemon, process id <4>:                -bd.
* daemon, process id:                    -bP.
* database: lookup:                      File and database lookups.
* database: maintenance:                 Database maintenance.
* Date: header:                          The Date header.
* DBM:                                   Single-key lookup types.
* DBM building:                          Making DBM files.
* DBM libraries:                         DBM libraries.
* debugging:                             -d<number>.
* debugging output:                      -df.
* default:                               Terminology.
* default configuration:                 The default configuration file.
* defaults for aliases:                  Alias file format.
* defaults for lookups:                  Default values in single-key lookups.
* deferred delivery, forcing:            Types of alias item.
* delay_after_cutoff:                    Long-term failures.
* delay_warning_condition:               Expansion variables.
* deliveries, maximum number of:         remote_max_parallel.
* delivery to single file:               Operational details for delivery to a new file.
* Delivery-date: header <1>:             delivery_date_remove.
* Delivery-date: header <2>:             The Delivery-date header.
* Delivery-date: header:                 delivery_date_add (transport).
* delivery: by external agent:           Using an external local delivery agent.
* delivery: cancelling all:              -Mmad <message id> <message id>.
* delivery: cancelling by address:       -Mmd <message id> <address> <address>.
* delivery: deferral:                    Delivery in detail.
* delivery: failure <1>:                 forbid_filter_reply (forwardfile).
* delivery: failure <2>:                 forbid_file.
* delivery: failure <3>:                 forbid_file (smartuser).
* delivery: failure <4>:                 forbid_pipe.
* delivery: failure <5>:                 forbid_pipe (smartuser).
* delivery: failure <6>:                 Delivery failures.
* delivery: failure:                     Delivery in detail.
* delivery: failure report <1>:          errmsg_file.
* delivery: failure report <2>:          Format of spool files.
* delivery: failure report <3>:          errors_copy.
* delivery: failure report <4>:          Life of a message.
* delivery: failure report <5>:          Delivery in detail.
* delivery: failure report <6>:          return_size_limit.
* delivery: failure report:              -E.
* delivery: failure report, discarding <1>: ignore_errmsg_errors.
* delivery: failure report, discarding:  ignore_errmsg_errors_after.
* delivery: failure, long-term:          Long-term failures.
* delivery: fake:                        Fake deliveries.
* delivery: first:                       Expansion conditions.
* delivery: forcing:                     -M <message id> <message id>.
* delivery: forcing deferral:            Types of alias item.
* delivery: forcing failure <1>:         Types of alias item.
* delivery: forcing failure:             The queue menu.
* delivery: from given sender:           -r.
* delivery: problems with:               Testing.
* delivery: procmail:                    Using an external local delivery agent.
* delivery: sorting remote:              remote_sort.
* delivery: to given domain:             -R<flags> <string>.
* delivery_date_remove:                  The Delivery-date header.
* dialup:                                Intermittently connected hosts.
* directing loop <1>:                    Types of alias item.
* directing loop:                        Delivery in detail.
* director::                             Drivers.
* director: skipping <1>:                Skipping directors and routers.
* director: skipping:                    Skipping directors.
* directories, multiple:                 split_spool_directory.
* directory creation <1>:                Operational details for delivery to a new file.
* directory creation <2>:                check_string (appendfile).
* directory creation <3>:                The appendfile transport.
* directory creation:                    Operational details for appending.
* disc space, checking <1>:              check_spool_space.
* disc space, checking:                  smtp_check_spool_space.
* discarded messages:                    Logging deliveries.
* DNS:                                   Query-style lookup types.
* DNS reverse lookup <1>:                helo_verify.
* DNS reverse lookup <2>:                Format of spool files.
* DNS reverse lookup <3>:                Main configuration settings.
* DNS reverse lookup:                    Expansion variables.
* dnsdb:                                 More about dnsdb.
* domain literal <1>:                    forbid_domain_literals.
* domain literal <2>:                    The ipliteral router.
* domain literal <3>:                    local_domains.
* domain literal:                        local_domains_include_host_literals.
* domain: definition:                    Terminology.
* domain: delivery to:                   -R<flags> <string>.
* domain: extraction:                    Expansion operators.
* domain: in alias file:                 include_domain (aliasfile).
* domain: in alias or forward file, preserving: qualify_preserve_domain.
* domain: in smartuser, preserving:      qualify_preserve_domain (smartuser).
* domain: list format:                   Domain lists.
* domain: virtual:                       Virtual domains.
* domainless addresses:                  Limitations.
* domainlist router:                     The domainlist router.
* dot handling <1>:                      strip_trailing_dot.
* dot handling:                          -oi.
* dots in local parts:                   Dots in local parts.
* driver specifications:                 Driver specifications.
* drivers:                               Drivers.
* duplicate addresses:                   Duplicate addresses.
* EACCES:                                ignore_eacces (forwardfile).
* editing configuration files:           Overriding build-time options for Exim.
* editing message body:                  -Meb <message id>.
* EDQUOT:                                Overriding build-time options for Exim.
* EHLO <1>:                              gethostbyname (smtp).
* EHLO <2>:                              Logging message reception.
* EHLO <3>:                              Outgoing SMTP over TCP/IP.
* EHLO:                                  helo_accept_junk_hosts.
* EHLO verification:                     Host verification.
* encrypted comparison:                  Expansion conditions.
* encrypted SMTP connections:            tls_advertise_hosts.
* encryption <1>:                        Encrypted SMTP connections using TLS/SSL.
* encryption:                            Including TLS/SSL encryption support.
* ENOSPC:                                Overriding build-time options for Exim.
* ENOTDIR:                               ignore_enotdir (forwardfile).
* Envelope-to: header <1>:               search_type (aliasfile).
* Envelope-to: header <2>:               batch (appendfile).
* Envelope-to: header <3>:               batch (lmtp).
* Envelope-to: header <4>:               The Envelope-to header.
* Envelope-to: header <5>:               batch (pipe).
* Envelope-to: header <6>:               envelope_to_add (transport).
* Envelope-to: header:                   envelope_to_remove.
* envelope_to_remove:                    The Envelope-to header.
* environment for local transports:      Environment for running local transports.
* environment for pipe transport <1>:    Environment variables.
* environment for pipe transport:        environment (pipe).
* ERRNO_QUOTA:                           Overriding build-time options for Exim.
* error messages::                       -E.
* error messages: customizing <1>:       Customizing prohibition messages.
* error messages: customizing <2>:       errmsg_file.
* error messages: customizing:           Customizing error and warning messages.
* error messages: discarding <1>:        ignore_errmsg_errors.
* error messages: discarding:            ignore_errmsg_errors_after.
* error reporting <1>:                   -oeq.
* error reporting <2>:                   -oem.
* error reporting <3>:                   -oee.
* error reporting <4>:                   -oep.
* error reporting:                       -oew.
* errors: in configuration file:         The Exim configuration file.
* errors: in outgoing SMTP:              Errors in outgoing SMTP.
* errors: skipping bad syntax <1>:       skip_syntax_errors.
* errors: skipping bad syntax:           Errors in forward files.
* errors_to:                             Using Exim to handle mailing lists.
* ETRN <1>:                              The ETRN command.
* ETRN <2>:                              smtp_etrn_command.
* ETRN <3>:                              smtp_etrn_hosts.
* ETRN:                                  Expansion variables.
* ETRN: command:                         smtp_etrn_command.
* ETRN: serializing:                     smtp_etrn_serialize.
* exceptions: alias defaults:            Types of alias item.
* exceptions: RBL checking:              rbl_hosts.
* exceptions: rejected recipients <1>:   Host checking using RBL.
* exceptions: rejected recipients <2>:   recipients_reject_except.
* exceptions: rejected recipients:       Other host checking.
* exec failure:                          freeze_exec_fail (pipe).
* exicyclog:                             Cycling log files.
* exigrep:                               Extracting log information.
* exim monitor:                          The Exim monitor.
* exim_dbmbuild:                         Making DBM files.
* exim_dumpdb:                           Database maintenance.
* exim_fixdb:                            Database maintenance.
* EXIM_GROUP:                            The Exim configuration file.
* exim_lock:                             Mailbox maintenance.
* exim_monitor/EDITME <1>:               Pre-building configuration.
* exim_monitor/EDITME:                   The Exim monitor.
* exim_tidydb:                           Database maintenance.
* EXIM_USER:                             The Exim configuration file.
* eximon:                                The Exim monitor.
* eximstats:                             Mail statistics.
* eximstats options:                     Mail statistics.
* exinext:                               Individual retry times.
* exiqsumm:                              Summarising the queue.
* exiwhat:                               Querying Exim processes.
* expansion of strings::                 String expansions.
* expansion of strings: alias data:      expand (aliasfile).
* expansion of strings: character translation: Expansion items.
* expansion of strings: conditions <1>:  Expansion items.
* expansion of strings: conditions:      Expansion conditions.
* expansion of strings: file lookup:     Expansion items.
* expansion of strings: headers:         Expansion items.
* expansion of strings: numeric comparison: Expansion conditions.
* expansion of strings: operators <1>:   Expansion items.
* expansion of strings: operators:       Expansion operators.
* expansion of strings: query lookup:    Expansion items.
* expansion of strings: string comparison: Expansion conditions.
* expansion of strings: substitution:    Expansion items.
* expansion of strings: testing:         Testing string expansions.
* expansion of strings: variables <1>:   Expansion items.
* expansion of strings: variables:       Expansion variables.
* EXPN <1>:                              The VRFY and EXPN and DEBUG commands.
* EXPN:                                  smtp_expn_hosts.
* external local delivery:               Using an external local delivery agent.
* external transports:                   Limitations.
* EXTRALIBS:                             Overriding build-time options for Exim.
* failing delivery, forcing:             Types of alias item.
* failure of exec:                       freeze_exec_fail (pipe).
* fallback <1>:                          fallback_hosts (smtp).
* fallback:                              fallback_hosts (director or router).
* fallover <1>:                          fallback_hosts (director or router).
* fallover:                              fallback_hosts (smtp).
* fifo (named pipe):                     allow_fifo (appendfile).
* file: appending:                       Operational details for appending.
* file: checking existing format:        file_format (appendfile).
* file: locking <1>:                     mbx_format (appendfile).
* file: locking:                         Operational details for appending.
* file: lookup <1>:                      Expansion items.
* file: lookup <2>:                      search_type (domainlist).
* file: lookup:                          File and database lookups.
* file: MBX format:                      mbx_format (appendfile).
* file: too many open:                   lookup_open_max.
* file: transport:                       message_filter_file_transport.
* filter: system filter <1>:             System-wide message filtering.
* filter: system filter:                 message_filter.
* filter: testing:                       -bf <filename>.
* filter: transport filter <1>:          Expansion variables.
* filter: transport filter <2>:          size_addition (smtp).
* filter: transport filter <3>:          Outgoing SMTP over TCP/IP.
* filter: transport filter <4>:          How the command is run.
* filter: transport filter:              transport_filter (transport).
* filter: user filter <1>:               filter (forwardfile).
* filter: user filter:                   Filter files.
* filtering all mail <1>:                System-wide automatic processing.
* filtering all mail:                    System-wide message filtering.
* first delivery:                        Expansion conditions.
* fixed point format:                    Fixed point number.
* fixing bad senders:                    Fixing bad senders.
* forcing delivery:                      -M <message id> <message id>.
* foreground delivery:                   -odf.
* format: address list:                  Address lists.
* format: alias file:                    Alias file format.
* format: configuration file:            Configuration file format.
* format: domain list:                   Domain lists.
* format: fixed point:                   Fixed point number.
* format: forward file:                  Forward file items.
* format: group name:                    User and group names.
* format: host list:                     Host lists.
* format: integer:                       Integer.
* format: list:                          List construction.
* format: message:                       -bm.
* format: octal integer:                 Octal integer.
* format: spool files:                   Format of spool files.
* format: string:                        String.
* format: time interval:                 Time interval.
* format: user name:                     User and group names.
* forward file::                         Reading forward files.
* forward file: backslash in:            Forward file items.
* forward file: ownership:               owners.
* forward file: testing:                 -bf <filename>.
* forward files: broken:                 skip_syntax_errors.
* forward files: repeated expansion:     Repeated forwarding expansion.
* forwardfile director <1>:              Current and home directories.
* forwardfile director <2>:              The forwardfile director.
* forwardfile director <3>:              Uids and gids.
* forwardfile director:                  Options common to the aliasfile and forwardfile directors.
* forwardfile: one-time expansion:       one_time.
* freezing messages <1>:                 -Mf <message id> <message id>.
* freezing messages:                     Additional commands for system filters.
* From: header <1>:                      The From header.
* From: header <2>:                      local_from_check.
* From: header:                          Trusted and admin users.
* frozen messages: <1>:                  -Mf <message id> <message id>.
* frozen messages: <2>:                  The system message filter.
* frozen messages: <3>:                  Watching the queue.
* frozen messages::                      -bp.
* frozen messages: display:              The queue display.
* frozen messages: forcing delivery <1>: -M <message id> <message id>.
* frozen messages: forcing delivery:     -R<flags> <string>.
* frozen messages: moving:               move_frozen_messages.
* frozen messages: spool data:           Format of spool files.
* frozen messages: thawing <1>:          -qffl.
* frozen messages: thawing <2>:          -Mt <message id> <message id>.
* frozen messages: thawing <3>:          Life of a message.
* frozen messages: thawing <4>:          The queue menu.
* frozen messages: thawing:              -qff.
* frozen messages: timing out:           timeout_frozen_after.
* gateway:                               Domainlist examples.
* gcc:                                   Overriding build-time options for Exim.
* generic options::                      Driver specifications.
* generic options: director <1>:         Generic options common to both directors and routers.
* generic options: director:             Additional generic options for directors.
* generic options: router <1>:           Additional generic options for routers.
* generic options: router:               Generic options common to both directors and routers.
* generic options: transport:            Generic options for transports.
* gid: caller:                           Expansion variables.
* gid: Exim's own <1>:                   exim_group.
* gid: Exim's own:                       Spool files.
* gid: forward file:                     The forwardfile director.
* gid: in spool file:                    Format of spool files.
* gid: local delivery <1>:               Environment for running local transports.
* gid: local delivery <2>:               Outgoing batched SMTP.
* gid: local delivery <3>:               group (director or router).
* gid: local delivery <4>:               group (autoreply).
* gid: local delivery:                   group (appendfile).
* gid: of originating user:              Expansion variables.
* gid: queryprogram:                     command_group (queryprogram).
* gid: system filter <1>:                The system message filter.
* gid: system filter:                    message_filter_file_transport.
* giving up on messages:                 -Mg <message id> <message id>.
* group name format:                     User and group names.
* groups, additional <1>:                ignore_status (pipe).
* groups, additional <2>:                group (lmtp).
* groups, additional <3>:                headers (autoreply).
* groups, additional:                    headers_remove (director or router).
* hash function: numeric:                Expansion operators.
* hash function: textual:                Expansion operators.
* header files:                          OS-specific header files.
* header syntax checking:                headers_check_syntax.
* header verification <1>:               headers_sender_verify.
* header verification:                   Header verification.
* headers: adding <1>:                   headers_add (transport).
* headers: adding <2>:                   headers_add (director or router).
* headers: adding:                       Adding and removing headers.
* headers: listing:                      -Mvh <message id>.
* headers: removing <1>:                 headers_remove (transport).
* headers: removing <2>:                 headers_remove (director or router).
* headers: removing:                     Adding and removing headers.
* headers: transporting:                 headers_only (transport).
* HELO <1>:                              Logging message reception.
* HELO <2>:                              Outgoing SMTP over TCP/IP.
* HELO <3>:                              gethostbyname (smtp).
* HELO:                                  helo_accept_junk_hosts.
* HELO verification:                     Host verification.
* HOME:                                  Environment variables.
* home directory <1>:                    The forwardfile director.
* home directory <2>:                    The localuser director.
* home directory <3>:                    Current and home directories.
* home directory <4>:                    The home directory.
* home directory <5>:                    Special treatment of home_directory and current_directory.
* home directory:                        ignore_enotdir (forwardfile).
* home_directory:                        Special treatment of home_directory and current_directory.
* HOST:                                  Environment variables.
* host: alias:                           Host lists.
* host: error:                           Errors in outgoing SMTP.
* host: heavily loaded:                  Exim on heavily loaded hosts.
* host: list format:                     Host lists.
* host: locally unique number:           localhost_number.
* host: lookup failures:                 Host lists.
* host: maximum number to try:           hosts_max_try (smtp).
* host: name <1>:                        host_lookup.
* host: name:                            Domain lists.
* host: name verification:               Host verification.
* host: randomized list <1>:             hosts_randomize (smtp).
* host: randomized list:                 hosts_randomize (domainlist).
* host: serialising connections:         serialize_hosts (smtp).
* host_accept_relay:                     Control of relaying.
* host_reject:                           Other host checking.
* host_reject_recipients:                Other host checking.
* hosts_treat_as_local:                  self (router).
* HP-UX:                                 gecos_name.
* hub:                                   Domainlist examples.
* id of message:                         Message reception.
* ident <1>:                             rfc1413_hosts.
* ident <2>:                             Incorporated code.
* ident <3>:                             Other host checking.
* ident:                                 Use of RFC 1413 identification in host lists.
* ignoring faulty addresses <1>:         skip_syntax_errors.
* ignoring faulty addresses:             Errors in forward files.
* included address list <1>:             Reading forward files.
* included address list <2>:             Forward file items.
* included address list:                 Types of alias item.
* incoming SMTP over TCP/IP:             Incoming SMTP messages over TCP/IP.
* incorporated code:                     Incorporated code.
* inetd <1>:                             Incoming SMTP messages over TCP/IP.
* inetd <2>:                             smtp_accept_max.
* inetd <3>:                             -bs.
* inetd:                                 -df.
* initgroups option:                     Uids and gids.
* installing exim:                       Installing commands and scripts.
* integer format <1>:                    Integer.
* integer format:                        Octal integer.
* interface address:                     -oMi <interface address>.
* interfaces, network:                   local_interfaces.
* intermittently connected hosts:        Intermittently connected hosts.
* IP address: <1>:                       local_domains_include_host_literals.
* IP address::                           local_interfaces.
* IP address: binding <1>:               local_interfaces.
* IP address: binding:                   hosts_randomize (smtp).
* IP address: discarding:                ignore_target_hosts (router).
* IP address: masking <1>:               Expansion operators.
* IP address: masking:                   Host lists.
* IP address: translating:               translate_ip_address (router).
* IP options:                            kill_ip_options.
* IP source routing <1>:                 kill_ip_options.
* IP source routing:                     IPv4 source routing.
* ipliteral router:                      The ipliteral router.
* iplookup router:                       The iplookup router.
* IPv6 <1>:                              gethostbyname (lookuphost).
* IPv6:                                  Including support for IPv6.
* IPv6 addresses in lists:               List construction.
* IPv6 DNS lookup:                       dns_ipv4_lookup.
* journal file:                          Life of a message.
* LDAP <1>:                              Overriding build-time options for Exim.
* LDAP <2>:                              More about LDAP.
* LDAP:                                  Query-style lookup types.
* length of login name:                  max_username_length.
* LF <1>:                                use_crlf (pipe).
* LF <2>:                                use_crlf (appendfile).
* LF <3>:                                Outgoing SMTP over TCP/IP.
* LF <4>:                                Incoming SMTP messages over TCP/IP.
* LF:                                    -dropcr.
* limitations:                           Limitations.
* linear search:                         Single-key lookup types.
* linefeed <1>:                          use_crlf (pipe).
* linefeed <2>:                          Outgoing SMTP over TCP/IP.
* linefeed <3>:                          Incoming SMTP messages over TCP/IP.
* linefeed <4>:                          use_crlf (appendfile).
* linefeed:                              -dropcr.
* link, symbolic <1>:                    The building process.
* link, symbolic <2>:                    Reading forward files.
* link, symbolic <3>:                    Multiple machine architectures and operating systems.
* link, symbolic <4>:                    Forward file items.
* link, symbolic <5>:                    Switching Exim on.
* link, symbolic <6>:                    allow_symlink (appendfile).
* link, symbolic <7>:                    Operational details for appending.
* link, symbolic:                        Setting options by program name.
* list: address list:                    Address lists.
* list: construction:                    List construction.
* list: domain list:                     Domain lists.
* list: host list:                       Host lists.
* list: negation:                        Domain lists.
* list: separator, changing:             List construction.
* listing: message body:                 -Mvb <message id>.
* listing: message headers:              -Mvh <message id>.
* listing: message log:                  -Mvl <message id>.
* listing: the queue:                    -bp.
* LMTP over TCP/IP:                      protocol (smtp).
* lmtp transport:                        The lmtp transport.
* lmtp: batch delivery:                  batch (lmtp).
* load average <1>:                      deliver_load_max.
* load average <2>:                      queue_only_load.
* load average:                          smtp_load_reserve.
* load, heavy:                           Exim on heavily loaded hosts.
* local address delivery:                -ql.
* local delivery <1>:                    Using an external local delivery agent.
* local delivery:                        -odqr.
* local delivery, definition:            Terminology.
* local domain, definition:              Terminology.
* local host: domains treated as:        hosts_treat_as_local.
* local host: MX pointing to <1>:        self (router).
* local host: MX pointing to:            The lookuphost router.
* local message reception:               -bm.
* local nameserver:                      Exim on heavily loaded hosts.
* local part: case of <1>:               Case of local parts.
* local part: case of:                   locally_caseless.
* local part: definition:                Terminology.
* local part: dots in:                   Dots in local parts.
* local part: prefix:                    Multiple user mailboxes.
* local part: starting with !:           Address lists.
* local part: suffix:                    Multiple user mailboxes.
* local SMTP input:                      -bs.
* local transports: environment:         Environment for running local transports.
* local transports: uid and gid <1>:     user (director or router).
* local transports: uid and gid <2>:     group (director or router).
* local transports: uid and gid <3>:     Uids and gids.
* local transports: uid and gid:         headers_remove (director or router).
* Local/eximon.conf <1>:                 Overriding build-time options for the monitor.
* Local/eximon.conf <2>:                 The Exim monitor.
* Local/eximon.conf:                     Pre-building configuration.
* Local/Makefile <1>:                    Pre-building configuration.
* Local/Makefile:                        Overriding build-time options for Exim.
* local_domains:                         Control of relaying.
* localhost_number:                      Message reception.
* localuser director <1>:                Uids and gids.
* localuser director <2>:                Current and home directories.
* localuser director:                    The localuser director.
* lock files <1>:                        file (appendfile).
* lock files:                            Testing.
* locking files <1>:                     mbx_format (appendfile).
* locking files <2>:                     Operational details for appending.
* locking files <3>:                     file (appendfile).
* locking files:                         lock_fcntl_timeout (appendfile).
* locking mailboxes:                     Mailbox maintenance.
* locking messages:                      Life of a message.
* log extraction:                        Extracting log information.
* log: all expanded addresses:           log_all_parents.
* log: arguments:                        log_arguments.
* log: cycling <1>:                      Cycling log files.
* log: cycling:                          Log cycling.
* log: destination:                      Log files.
* log: distinguished name <1>:           Configuring Exim to use TLS as a server.
* log: distinguished name:               Configuring Exim to use TLS as a client.
* log: level:                            Log level.
* log: level for queue run:              log_queue_run_level.
* log: message <1>:                      Life of a message.
* log: message:                          Message log.
* log: process:                          What is Exim doing?.
* log: SMTP connections:                 log_smtp_connections.
* log: SMTP syntax errors:               log_smtp_syntax_errors.
* log: tail:                             The log display.
* log: TLS cipher <1>:                   Configuring Exim to use TLS as a server.
* log: TLS cipher:                       Configuring Exim to use TLS as a client.
* log: to file:                          Log files.
* log: to syslog:                        Log files.
* log: types:                            Log files.
* log: unknown SMTP commands:            log_smtp_syntax_errors.
* log_received_recipients:               Logging message reception.
* log_received_sender:                   Logging message reception.
* log_subject:                           Logging message reception.
* lookup, in expanded string:            Expansion items.
* lookup::                               File and database lookups.
* lookup: *:                             Default values in single-key lookups.
* lookup: *@:                            Default values in single-key lookups.
* lookup: caching:                       Lookup caching.
* lookup: cdb:                           Single-key lookup types.
* lookup: dbm:                           Single-key lookup types.
* lookup: dbm, terminating zero:         Single-key lookup types.
* lookup: dbmnz:                         Single-key lookup types.
* lookup: default values:                Default values in single-key lookups.
* lookup: DNS:                           Query-style lookup types.
* lookup: dnsdb:                         More about dnsdb.
* lookup: inclusion in binary:           Overriding build-time options for Exim.
* lookup: LDAP <1>:                      Query-style lookup types.
* lookup: LDAP:                          More about LDAP.
* lookup: lsearch:                       Single-key lookup types.
* lookup: MySQL <1>:                     Query-style lookup types.
* lookup: MySQL:                         More about MySQL and PostgreSQL.
* lookup: NIS:                           Single-key lookup types.
* lookup: NIS+ <1>:                      More about NIS+.
* lookup: NIS+:                          Query-style lookup types.
* lookup: partial matching:              Partial matching in single-key lookups.
* lookup: PostgreSQL:                    Query-style lookup types.
* lookup: quoting:                       Quoting lookup data.
* lookup: single key:                    Single-key lookup types.
* lookup: temporary error:               Temporary errors in lookups.
* lookup: wildcard:                      Default values in single-key lookups.
* lookuphost router:                     The lookuphost router.
* loop: caused by fail:                  Additional commands for system filters.
* loop: directing <1>:                   Types of alias item.
* loop: directing:                       Delivery in detail.
* loop: forward file:                    Forward file items.
* loop: in lookups:                      Address lists.
* loop: local host <1>:                  allow_localhost (smtp).
* loop: local host:                      local_interfaces.
* loop: prevention:                      received_headers_max.
* loop: while file testing:              Operational details for appending.
* lower casing <1>:                      Making DBM files.
* lower casing <2>:                      The aliasfile director.
* lower casing <3>:                      locally_caseless.
* lower casing <4>:                      Rewriting patterns.
* lower casing:                          Expansion operators.
* macro setting:                         -D<macro>=<value>.
* macros in configuration file:          Macros in the configuration file.
* mail delivery:                         Message reception.
* mail filter:                           Filter files.
* mail hub:                              Domainlist examples.
* mail loop prevention:                  received_headers_max.
* mail relaying:                         host_accept_relay.
* mailbox: maintenance:                  Mailbox maintenance.
* mailbox: MMDF format:                  check_string (appendfile).
* mailbox: multiple <1>:                 prefix (director).
* mailbox: multiple:                     Multiple user mailboxes.
* mailbox: size warning:                 quota_warn_threshold (appendfile).
* mailbox: symbolic link <1>:            Operational details for appending.
* mailbox: symbolic link:                allow_symlink (appendfile).
* maildir format:                        Operational details for delivery to a new file.
* mailing lists::                        Using Exim to handle mailing lists.
* mailing lists: closed <1>:             Closed mailing lists.
* mailing lists: closed:                 senders (director or router).
* mailing lists: one-time expansion:     one_time.
* mailing lists: re-expansion:           Re-expansion of mailing lists.
* mailmaster:                            Terminology.
* mailq:                                 Setting options by program name.
* mailstore format:                      Operational details for delivery to a new file.
* main configuration:                    Main configuration.
* main log:                              Log files.
* maintaining Exim's database:           Database maintenance.
* make:                                  The building process.
* mask: IP address <1>:                  Expansion operators.
* mask: IP address:                      Host lists.
* maximum incoming SMTP:                 smtp_accept_max.
* maximum number of hosts:               hosts_max_try (smtp).
* maximum recipients:                    recipients_max.
* maximum retry interval:                Retry rules.
* MD5 hash <1>:                          Expansion conditions.
* MD5 hash:                              Expansion operators.
* memmove:                               Limitations.
* memory allocation:                     -dm.
* message size <1>:                      -bp.
* message size:                          size_addition (smtp).
* message size limit <1>:                return_size_limit.
* message size limit:                    message_size_limit.
* Message-id: header:                    The Message-id header.
* message: adding recipients:            -Mar <message id> <address> <address>.
* message: age of:                       Expansion variables.
* message: body in expansion:            Expansion variables.
* message: body line count:              Expansion variables.
* message: body size:                    Expansion variables.
* message: body, visible size:           message_body_visible.
* message: changing sender:              -Mes <message id> <address>.
* message: discarded:                    Logging deliveries.
* message: editing body of:              -Meb <message id>.
* message: error:                        Errors in outgoing SMTP.
* message: format:                       -bm.
* message: id <1>:                       localhost_number.
* message: id:                           Message reception.
* message: listing body of:              -Mvb <message id>.
* message: log <1>:                      Life of a message.
* message: log:                          Message log.
* message: log listing:                  -Mvl <message id>.
* message: processing:                   Message processing.
* message: queueing <1>:                 queue_only.
* message: queueing <2>:                 smtp_accept_queue.
* message: queueing <3>:                 queue_only_file.
* message: queueing <4>:                 queue_only_load.
* message: queueing:                     smtp_accept_queue_per_connection.
* message: size:                         Expansion variables.
* message: transporting body only:       body_only (transport).
* message: transporting headers only:    headers_only (transport).
* message_id_header_text:                The Message-id header.
* MMDF format mailbox:                   check_string (appendfile).
* monitor <1>:                           Incorporated code.
* monitor:                               The Exim monitor.
* monitor window size:                   Main action buttons.
* more option <1>:                       self (router).
* more option:                           host_find_failed (domainlist).
* msglog directory:                      Message log.
* multiple mailboxes <1>:                Multiple user mailboxes.
* multiple mailboxes:                    prefix (director).
* multiple SMTP deliveries <1>:          -oB <n>.
* multiple SMTP deliveries <2>:          Exim on the intermittently connected host.
* multiple SMTP deliveries <3>:          authenticate_hosts (smtp).
* multiple SMTP deliveries <4>:          -Mar <message id> <address> <address>.
* multiple SMTP deliveries <5>:          -q.
* multiple SMTP deliveries:              -qq.
* multiple spool directories:            split_spool_directory.
* MX pointing to IP address:             allow_mx_to_ip.
* MX pointing to local host <1>:         The lookuphost router.
* MX pointing to local host:             self (router).
* MySQL <1>:                             Query-style lookup types.
* MySQL:                                 More about MySQL and PostgreSQL.
* name of sender:                        -F <string>.
* named pipe (fifo):                     allow_fifo (appendfile).
* negation: in address lists:            Address lists.
* negation: in domain lists:             Domain lists.
* negation: in host lists:               Host lists.
* network interfaces <1>:                local_interfaces.
* network interfaces:                    local_domains_include_host_literals.
* new drivers, adding:                   Adding new drivers or lookup types.
* newaliases:                            Setting options by program name.
* NFS: <1>:                              file (forwardfile).
* NFS: <2>:                              freeze_missing_include.
* NFS::                                  require_files (director or router).
* NFS: lock file <1>:                    file (appendfile).
* NFS: lock file <2>:                    require_lockfile (appendfile).
* NFS: lock file <3>:                    use_lockfile (appendfile).
* NFS: lock file:                        Operational details for appending.
* NFS: root access:                      seteuid (forwardfile).
* NIS <1>:                               Single-key lookup types.
* NIS:                                   Overriding build-time options for Exim.
* NIS+ <1>:                              Query-style lookup types.
* NIS+ <2>:                              More about NIS+.
* NIS+:                                  Overriding build-time options for Exim.
* non-immediate delivery:                -odq.
* number of deliveries:                  remote_max_parallel.
* numeric comparison:                    Expansion conditions.
* one-time aliasing/forwarding expansion: one_time.
* open files, too many:                  lookup_open_max.
* OpenSSL:                               Encrypted SMTP connections using TLS/SSL.
* operating system type:                 Overriding build-time options for Exim.
* options: aliasfile <1>:                Options common to the aliasfile and forwardfile directors.
* options: aliasfile:                    Aliasfile private options.
* options: appendfile:                   Private options for appendfile.
* options: command line:                 The Exim command line.
* options: command line, terminating:    -<hyphen>.
* options: configuration:                -bP.
* options: director:                     -bP.
* options: domainlist:                   The domainlist router.
* options: forwardfile <1>:              Options common to the aliasfile and forwardfile directors.
* options: forwardfile:                  Forwardfile private options.
* options: generic:                      Driver specifications.
* options: generic director <1>:         Generic options common to both directors and routers.
* options: generic director:             Additional generic options for directors.
* options: generic router <1>:           Additional generic options for routers.
* options: generic router:               Generic options common to both directors and routers.
* options: generic transport:            Generic options for transports.
* options: iplookup:                     The iplookup router.
* options: lookuphost:                   The lookuphost router.
* options: pipe:                         Private options for pipe.
* options: queryprogram:                 The queryprogram router.
* options: router:                       -bP.
* options: smartuser:                    The smartuser director.
* options: smtp:                         The smtp transport.
* options: transport:                    -bP.
* os.h:                                  OS-specific header files.
* outgoing SMTP over TCP/IP:             Outgoing SMTP over TCP/IP.
* overriding build-time options:         Overriding build-time options for Exim.
* ownership: alias file:                 owners.
* ownership: configuration file:         The Exim configuration file.
* ownership: forward file:               owners.
* packet radio:                          translate_ip_address (router).
* PAM:                                   Expansion conditions.
* panic log:                             Log files.
* partial matching:                      Partial matching in single-key lookups.
* password file, doing without:          Specifying a transport for aliasfile.
* PCRE:                                  Incorporated code.
* periodic queue running:                -q <time>.
* Perl: calling from Exim:               Embedded Perl.
* Perl: embedded <1>:                    Embedded Perl.
* Perl: embedded <2>:                    -pd.
* Perl: embedded <3>:                    Overriding build-time options for Exim.
* Perl: embedded:                        -ps.
* Perl: use in expanded string:          Expansion items.
* perl_at_start:                         Embedded Perl.
* perl_startup:                          Embedded Perl.
* pid, of daemon <1>:                    Changing the configuration.
* pid, of daemon <2>:                    -q <time>.
* pid, of daemon <3>:                    -bP.
* pid, of daemon <4>:                    -bd.
* pid, of daemon:                        -oX <number>.
* pipe transport <1>:                    The pipe transport.
* pipe transport <2>:                    message_filter_pipe_transport.
* pipe transport <3>:                    Current and home directories.
* pipe transport:                        Uids and gids.
* pipe: batch delivery:                  batch (pipe).
* pipe: control of commands <1>:         How the command is run.
* pipe: control of commands:             allow_commands (pipe).
* pipe: duplicated:                      Duplicate addresses.
* pipe: environment <1>:                 environment (pipe).
* pipe: environment:                     Environment variables.
* pipe: failure of exec:                 freeze_exec_fail (pipe).
* pipe: logging output:                  log_defer_output (pipe).
* pipe: named (fifo):                    allow_fifo (appendfile).
* pipe: path:                            How the command is run.
* pipe: returned data:                   Returned status and data.
* pipe: temporary failure:               temp_errors (pipe).
* plaintext authenticator:               The plaintext authenticator.
* policy controls:                       Other policy controls on incoming mail.
* port: iplookup router:                 port (iplookup).
* port: logging:                         log_incoming_port.
* port: receiving TCP/IP:                -oX <number>.
* port: sending TCP/IP:                  port (smtp).
* PostgreSQL <1>:                        More about MySQL and PostgreSQL.
* PostgreSQL:                            Query-style lookup types.
* postmaster <1>:                        Terminology.
* postmaster <2>:                        Other host checking.
* postmaster <3>:                        errors_address.
* postmaster:                            Host checking using RBL.
* pre-building configuration:            Pre-building configuration.
* preserve_message_logs:                 Message log.
* preserving domain in aliasing or forwarding: qualify_preserve_domain.
* preserving domain in smartuser:        qualify_preserve_domain (smartuser).
* primary host name:                     Domain lists.
* primary_hostname:                      Domain lists.
* printing characters:                   print_topbitchars.
* private options:                       Driver specifications.
* privilege, running without:            Running Exim without privilege.
* privileged user:                       Privileged users.
* process: log:                          What is Exim doing?.
* process: querying:                     Querying Exim processes.
* procmail <1>:                          The localuser director.
* procmail:                              Using an external local delivery agent.
* prohibition messages:                  Customizing prohibition messages.
* prohibition_message:                   Customizing prohibition messages.
* protocol:                              -oMr <protocol name>.
* qualify_domain:                        Unqualified addresses.
* qualify_recipient:                     Unqualified addresses.
* queryprogram router:                   The queryprogram router.
* queue-runner <1>:                      Terminology.
* queue-runner <2>:                      Setting options by program name.
* queue-runner <3>:                      -bd.
* queue-runner <4>:                      -q <time>.
* queue-runner <5>:                      -q.
* queue-runner:                          Delivery in detail.
* queue-runners, maximum number of:      queue_run_max.
* queue: definition:                     Terminology.
* queue: display:                        The queue display.
* queue: double scanning:                -qq.
* queue: forcing:                        -qf.
* queue: listing:                        -bp.
* queue: local address delivery:         -ql.
* queue: log level for run:              log_queue_run_level.
* queue: routing:                        -qq.
* queue: running <1>:                    -q <time>.
* queue: running <2>:                    -R<flags> <string>.
* queue: running:                        -q.
* queue: running, detecting:             Expansion conditions.
* queue: summary:                        Summarising the queue.
* queueing incoming messages <1>:        smtp_accept_queue_per_connection.
* queueing incoming messages <2>:        queue_only.
* queueing incoming messages <3>:        queue_only_file.
* queueing incoming messages <4>:        smtp_accept_queue.
* queueing incoming messages:            queue_only_load.
* quota: imposed by Exim:                quota (appendfile).
* quota: warning threshold:              quota_warn_threshold (appendfile).
* quoting: in lookups:                   Quoting lookup data.
* quoting: in pipe command:              How the command is run.
* quoting: in string expansions:         Expansion operators.
* quoting: lookup-specific:              Expansion operators.
* quoting: regular expressions:          Expansion operators.
* randomized host list <1>:              hosts_randomize (domainlist).
* randomized host list:                  hosts_randomize (smtp).
* RBL <1>:                               rbl_domains.
* RBL <2>:                               Host checking using RBL.
* RBL:                                   Customizing prohibition messages.
* rbl_domains:                           Host checking using RBL.
* rbl_hosts:                             Host checking using RBL.
* rbl_reject_recipients:                 Host checking using RBL.
* rbl_warn_header:                       Host checking using RBL.
* realtime blocking list <1>:            Host checking using RBL.
* realtime blocking list <2>:            rbl_domains.
* realtime blocking list:                Customizing prohibition messages.
* Received: header:                      The Received header.
* receiver verification:                 Receiver verification.
* recipient error:                       Errors in outgoing SMTP.
* recipients::                           -t.
* recipients: adding:                    -Mar <message id> <address> <address>.
* recipients: maximum:                   recipients_max.
* recipients: removing:                  -Mmd <message id> <address> <address>.
* recipients_reject_except:              Host checking using RBL.
* regular expressions: in domain list:   Domain lists.
* regular expressions: library <1>:      Regular expressions.
* regular expressions: library:          Incorporated code.
* regular expressions: quoting:          Expansion operators.
* reject log <1>:                        The reject log.
* reject log:                            Log files.
* rejection by sender:                   Sender checking.
* rejection messages:                    Customizing prohibition messages.
* relay_domains:                         Control of relaying.
* relay_match_host_or_sender:            Control of relaying.
* relaying: control by sender:           Control of relaying.
* relaying: control of <1>:              Control of relaying.
* relaying: control of:                  host_accept_relay.
* relaying: sender or host:              Control of relaying.
* relaying: testing configuration:       -bh <IP address>.
* remote delivery, definition:           Terminology.
* remote domain, definition:             Terminology.
* removing messages:                     -Mrm <message id> <message id>.
* removing recipients:                   -Mmd <message id> <address> <address>.
* repeated alias expansion:              Repeated alias expansion.
* repeated forwarding expansion:         Repeated forwarding expansion.
* retry: algorithms:                     Retry rules.
* retry: configuration:                  Retry configuration.
* retry: configuration testing:          -brt.
* retry: interval, maximum:              Retry rules.
* retry: rules:                          Retry rules.
* retry: time not reached <1>:           Other log entries.
* retry: time not reached:               Retry configuration.
* retry: times:                          Individual retry times.
* retry_data_expire:                     Timeout of retry data.
* retry_interval_max:                    Retry rules.
* Return-path: header <1>:               return_path_remove.
* Return-path: header <2>:               return_path_add (transport).
* Return-path: header:                   The Return-path header.
* return_path_remove:                    The Return-path header.
* reverse DNS lookup <1>:                Format of spool files.
* reverse DNS lookup <2>:                helo_verify.
* reverse DNS lookup <3>:                Expansion variables.
* reverse DNS lookup:                    Main configuration settings.
* rewriting: addresses <1>:              Address rewriting.
* rewriting: addresses:                  Rewriting addresses.
* rewriting: at transport time:          headers_rewrite (transport).
* rewriting: bang paths:                 Rewriting examples.
* rewriting: flags:                      Flags specifying which headers and envelope addresses to rewrite.
* rewriting: headers:                    rewrite_headers (lookuphost).
* rewriting: patterns:                   Rewriting patterns.
* rewriting: replacements:               Rewriting replacements.
* rewriting: rules:                      Rewriting rules.
* rewriting: testing <1>:                -brw.
* rewriting: testing <2>:                log_rewrites.
* rewriting: testing:                    Testing the rewriting rules that apply on input.
* rewriting: whole addresses:            Flags controlling the rewriting process.
* RFC 1413 <1>:                          Incorporated code.
* RFC 1413 <2>:                          rfc1413_hosts.
* RFC 1413 <3>:                          Other host checking.
* RFC 1413:                              Use of RFC 1413 identification in host lists.
* rmail:                                 Setting options by program name.
* root privilege:                        Root privilege.
* router::                               Drivers.
* router: skipping:                      Skipping directors and routers.
* routing timeout:                       pass_on_timeout (router).
* routing whole queue:                   -qq.
* rsmtp:                                 Setting options by program name.
* run time configuration <1>:            -C <filename>.
* run time configuration:                The Exim configuration file.
* runq:                                  Setting options by program name.
* search_parents:                        dns_search_parents (smtp).
* security <1>:                          Security considerations.
* security:                              Forward file items.
* self option <1>:                       Skipping directors and routers.
* self option:                           more (director or router).
* sender: address <1>:                   The UUCP From line.
* sender: address:                       -f <address>.
* sender: authenticated:                 Expansion variables.
* sender: changing:                      -Mes <message id> <address>.
* sender: gid:                           Expansion variables.
* Sender: header <1>:                    local_from_check.
* Sender: header <2>:                    The Sender header.
* Sender: header:                        Trusted and admin users.
* sender: host address:                  -oMa <host address>.
* sender: host name:                     -oMs <host name>.
* sender: ident string:                  -oMt <ident string>.
* sender: name:                          -F <string>.
* sender: rejection:                     Sender checking.
* sender: source of:                     -bs.
* sender: uid:                           Expansion variables.
* sender: verification <1>:              sender_verify.
* sender: verification:                  Sender verification.
* sender_address_relay:                  Control of relaying.
* sender_reject:                         Sender checking.
* sender_reject_recipients:              Sender checking.
* serialising connections:               serialize_hosts (smtp).
* seteuid <1>:                           Forward file items.
* seteuid:                               Root privilege.
* setresuid:                             Root privilege.
* setuid <1>:                            Root privilege.
* setuid:                                Installing commands and scripts.
* shadow transport:                      shadow_transport (transport).
* SIGHUP <1>:                            Changing the configuration.
* SIGHUP:                                -bd.
* SIGUSR1 <1>:                           What is Exim doing?.
* SIGUSR1:                               Querying Exim processes.
* SIZE:                                  Outgoing SMTP over TCP/IP.
* size limit:                            message_size_limit.
* size limit of bounce:                  return_size_limit.
* size of mailbox:                       quota_warn_threshold (appendfile).
* size of message <1>:                   message_size_limit.
* size of message <2>:                   Logging message reception.
* size of message <3>:                   size_addition (smtp).
* size of message <4>:                   -bp.
* size of message <5>:                   Expansion variables.
* size of message:                       return_size_limit.
* size of monitor window:                Main action buttons.
* skipping directors <1>:                Skipping directors and routers.
* skipping directors:                    Skipping directors.
* skipping faulty addresses <1>:         skip_syntax_errors.
* skipping faulty addresses:             Errors in forward files.
* skipping routers:                      Skipping directors and routers.
* smart host:                            Domainlist examples.
* smartuser director <1>:                The smartuser director.
* smartuser director:                    Uids and gids.
* smtp transport:                        The smtp transport.
* SMTP: authentication: configuration:   SMTP authentication.
* SMTP: batched incoming <1>:            -bS.
* SMTP: batched incoming <2>:            Sender verification.
* SMTP: batched incoming:                Incoming batched SMTP.
* SMTP: batched outgoing <1>:            Outgoing batched SMTP.
* SMTP: batched outgoing:                Domainlist examples.
* SMTP: batching over TCP/IP:            Outgoing SMTP over TCP/IP.
* SMTP: DEBUG:                           The VRFY and EXPN and DEBUG commands.
* SMTP: delaying delivery:               -odqs.
* SMTP: EHLO:                            Host verification.
* SMTP: encrypted connection:            tls_advertise_hosts.
* SMTP: encryption:                      Encrypted SMTP connections using TLS/SSL.
* SMTP: errors in outgoing:              Errors in outgoing SMTP.
* SMTP: ETRN <1>:                        The ETRN command.
* SMTP: ETRN:                            smtp_etrn_hosts.
* SMTP: EXPN:                            The VRFY and EXPN and DEBUG commands.
* SMTP: HELO:                            Host verification.
* SMTP: host checking:                   Other host checking.
* SMTP: incoming call count <1>:         smtp_accept_reserve.
* SMTP: incoming call count <2>:         smtp_accept_max.
* SMTP: incoming call count:             smtp_accept_queue.
* SMTP: incoming over TCP/IP:            Incoming SMTP messages over TCP/IP.
* SMTP: local incoming:                  Incoming local SMTP.
* SMTP: local input:                     -bs.
* SMTP: logging connections:             log_smtp_connections.
* SMTP: logging syntax errors:           log_smtp_syntax_errors.
* SMTP: multiple deliveries <1>:         -q.
* SMTP: multiple deliveries <2>:         authenticate_hosts (smtp).
* SMTP: multiple deliveries <3>:         -Mar <message id> <address> <address>.
* SMTP: multiple deliveries <4>:         -qq.
* SMTP: multiple deliveries <5>:         -oB <n>.
* SMTP: multiple deliveries:             Exim on the intermittently connected host.
* SMTP: outgoing over TCP/IP:            Outgoing SMTP over TCP/IP.
* SMTP: passed channel <1>:              Exim on the intermittently connected host.
* SMTP: passed channel <2>:              authenticate_hosts (smtp).
* SMTP: passed channel <3>:              -qq.
* SMTP: passed channel:                  -q.
* SMTP: passed connection:               Outgoing SMTP over TCP/IP.
* SMTP: passing channel <1>:             -Mar <message id> <address> <address>.
* SMTP: passing channel:                 -oA <file name>.
* SMTP: rewriting malformed addresses:   The SMTP-time rewriting flag.
* SMTP: SIZE <1>:                        size_addition (smtp).
* SMTP: SIZE:                            transport_filter (transport).
* SMTP: STARTTLS command:                tls_advertise_hosts.
* SMTP: syntax errors, logging:          log_smtp_syntax_errors.
* SMTP: testing incoming:                -bh <IP address>.
* SMTP: timeout <1>:                     The smtp transport.
* SMTP: timeout:                         smtp_receive_timeout.
* SMTP: unknown commands, logging:       log_smtp_syntax_errors.
* SMTP: VRFY:                            The VRFY and EXPN and DEBUG commands.
* SMTP: welcome banner:                  smtp_banner.
* smtp_accept_max:                       What is Exim doing?.
* smtp_etrn_command <1>:                 Expansion variables.
* smtp_etrn_command:                     The ETRN command.
* sorting remote deliveries:             remote_sort.
* source routing: in email address <1>:  percent_hack_domains.
* source routing: in email address:      collapse_source_routes.
* source routing: in IP packets <1>:     kill_ip_options.
* source routing: in IP packets:         IPv4 source routing.
* split spool directories:               split_spool_directory.
* spool: checking space <1>:             check_spool_space.
* spool: checking space:                 smtp_check_spool_space.
* spool: directory:                      Setting up the spool directory.
* spool: file locked:                    Other log entries.
* spool: files <1>:                      Message reception.
* spool: files <2>:                      Format of spool files.
* spool: files:                          Spool files.
* spool: format of:                      Format of spool files.
* spool: multiple directories:           split_spool_directory.
* spool: splitting directory:            split_spool_directory.
* sprintf <1>:                           Limitations.
* sprintf:                               Use of sprintf().
* src/EDITME:                            Pre-building configuration.
* statistics:                            Mail statistics.
* statvfs function:                      The stripcharts.
* STDERR_FILE <1>:                       -df.
* STDERR_FILE:                           Overriding build-time options for Exim.
* strerror:                              Limitations.
* string: case forcing:                  Expansion operators.
* string: comparison:                    Expansion conditions.
* string: expansions:                    String expansions.
* string: format:                        String.
* string: hashing:                       Expansion operators.
* stripchart:                            The stripcharts.
* substr:                                Expansion operators.
* substring extraction:                  Expansion operators.
* SunOS4:                                kill_ip_options.
* SUPPORT_TLS:                           Including TLS/SSL encryption support.
* switching on:                          Switching Exim on.
* symbolic link <1>:                     Operational details for appending.
* symbolic link <2>:                     Forward file items.
* symbolic link <3>:                     Setting options by program name.
* symbolic link <4>:                     Switching Exim on.
* symbolic link <5>:                     The building process.
* symbolic link <6>:                     Multiple machine architectures and operating systems.
* symbolic link <7>:                     Reading forward files.
* symbolic link:                         allow_symlink (appendfile).
* syntax checking headers:               headers_check_syntax.
* syntax of common options:              Common option syntax.
* syslog:                                Log files.
* system filter <1>:                     System-wide automatic processing.
* system filter:                         System-wide message filtering.
* system filter, testing:                -bF <filename>.
* system log:                            Log files.
* tail of log:                           The log display.
* TCP/IP incoming port:                  -oX <number>.
* TCP/IP outgoing port:                  port (smtp).
* tcpwrappers:                           Use of tcpwrappers.
* tdb:                                   DBM libraries.
* testing::                              Testing.
* testing: addresses <1>:                expn (director).
* testing: addresses:                    -bt.
* testing: filter file:                  -bf <filename>.
* testing: forward file:                 -bf <filename>.
* testing: incoming SMTP:                -bh <IP address>.
* testing: regular expressions:          Testing regular expressions.
* testing: relay control:                -bh <IP address>.
* testing: retry configuration:          -brt.
* testing: rewriting <1>:                Testing the rewriting rules that apply on input.
* testing: rewriting <2>:                log_rewrites.
* testing: rewriting:                    -brw.
* testing: string expansion:             Testing string expansions.
* testing: variables in drivers <1>:     debug_print (transport).
* testing: variables in drivers:         debug_print (director or router).
* thawing messages <1>:                  -Mt <message id> <message id>.
* thawing messages <2>:                  The queue menu.
* thawing messages <3>:                  -qff.
* thawing messages:                      auto_thaw.
* time interval format:                  Time interval.
* time zone:                             timezone.
* timeout: blocking:                     lock_fcntl_timeout (appendfile).
* timeout: frozen messages:              timeout_frozen_after.
* timeout: local message:                accept_timeout.
* timeout: non-blocking:                 lock_fcntl_timeout (appendfile).
* timeout: non-SMTP input:               -or <time>.
* timeout: of router:                    pass_on_timeout (router).
* timeout: retry data:                   Timeout of retry data.
* timeout: SMTP <1>:                     The smtp transport.
* timeout: SMTP:                         smtp_receive_timeout.
* timestamps:                            timestamps_utc.
* TLS: <1>:                              Including TLS/SSL encryption support.
* TLS: <2>:                              tls_advertise_hosts.
* TLS: <3>:                              tls_certificate (smtp).
* TLS::                                  Encrypted SMTP connections using TLS/SSL.
* TLS: avoiding for certain hosts:       hosts_avoid_tls (smtp).
* TLS: requiring for certain servers:    hosts_require_tls (smtp).
* tmail:                                 prefix (pipe).
* To: header <1>:                        always_bcc.
* To: header <2>:                        -t.
* To: header:                            The To header.
* too many open files:                   lookup_open_max.
* top bit <1>:                           accept_8bitmime.
* top bit <2>:                           -B<type>.
* top bit:                               print_topbitchars.
* trailing dot:                          strip_trailing_dot.
* trailing period:                       strip_trailing_dot.
* transport::                            Drivers.
* transport: appendfile:                 The appendfile transport.
* transport: autoreply:                  The autoreply transport.
* transport: body only:                  body_only (transport).
* transport: external:                   Limitations.
* transport: filter <1>:                 size_addition (smtp).
* transport: filter <2>:                 Expansion variables.
* transport: filter <3>:                 transport_filter (transport).
* transport: filter <4>:                 Outgoing SMTP over TCP/IP.
* transport: filter <5>:                 Expansion variables.
* transport: filter:                     How the command is run.
* transport: header rewriting:           headers_rewrite (transport).
* transport: headers only:               headers_only (transport).
* transport: lmtp:                       The lmtp transport.
* transport: local <1>:                  headers_remove (director or router).
* transport: local <2>:                  user (director or router).
* transport: local <3>:                  group (director or router).
* transport: local:                      Uids and gids.
* transport: pipe:                       The pipe transport.
* transport: shadow:                     shadow_transport (transport).
* transport: smtp:                       The smtp transport.
* trusted user <1>:                      -f <address>.
* trusted user <2>:                      Trusted and admin users.
* trusted user <3>:                      -oMa <host address>.
* trusted user <4>:                      -oMi <interface address>.
* trusted user <5>:                      -oMr <protocol name>.
* trusted user <6>:                      -oMs <host name>.
* trusted user <7>:                      -oMt <ident string>.
* trusted user <8>:                      untrusted_set_sender.
* trusted user:                          Privileged users.
* uid: caller:                           Expansion variables.
* uid: Exim's own <1>:                   exim_user.
* uid: Exim's own:                       Spool files.
* uid: forward file:                     The forwardfile director.
* uid: in spool file:                    Format of spool files.
* uid: local delivery <1>:               user (lmtp).
* uid: local delivery <2>:               group (pipe).
* uid: local delivery <3>:               Environment for running local transports.
* uid: local delivery <4>:               user (appendfile).
* uid: local delivery <5>:               user (director or router).
* uid: local delivery <6>:               Outgoing batched SMTP.
* uid: local delivery <7>:               user (autoreply).
* uid: local delivery <8>:               user (pipe).
* uid: local delivery <9>:               pipe_as_creator (pipe).
* uid: local delivery:                   group (lmtp).
* uid: of originating user:              Expansion variables.
* uid: queryprogram:                     command_user (queryprogram).
* uid: system filter <1>:                message_filter_reply_transport.
* uid: system filter:                    The system message filter.
* uid: unknown caller:                   trusted_users.
* unfreezing messages <1>:               -Mt <message id> <message id>.
* unfreezing messages <2>:               auto_thaw.
* unfreezing messages:                   The queue menu.
* unknown host name:                     Host lists.
* unprivileged running:                  Running Exim without privilege.
* unqualified addresses <1>:             sender_unqualified_hosts.
* unqualified addresses <2>:             receiver_unqualified_hosts.
* unqualified addresses:                 Unqualified addresses.
* upper casing:                          Expansion operators.
* USE_DB <1>:                            DBM libraries.
* USE_DB:                                Making DBM files.
* USE_TCP_WRAPPERS:                      Use of tcpwrappers.
* user name format:                      User and group names.
* user name, maximum length:             max_username_length.
* users: admin:                          Trusted and admin users.
* users: trusted:                        Trusted and admin users.
* UTC:                                   timestamps_utc.
* utilities:                             Exim utilities.
* UUCP <1>:                              Domainlist examples.
* UUCP <2>:                              The UUCP From line.
* UUCP:                                  -dropcr.
* UUCP, `From' line <1>:                 -bm.
* UUCP, `From' line <2>:                 ignore_fromline_hosts.
* UUCP, `From' line <3>:                 The UUCP From line.
* UUCP, `From' line:                     uucp_from_pattern.
* uucp_from_pattern:                     The UUCP From line.
* uucp_from_sender:                      The UUCP From line.
* vacation processing:                   Simplified vacation processing.
* Variable Envelope Return Paths:        Variable Envelope Return Paths (VERP).
* verifying: addresses:                  -bv.
* verifying: headers <1>:                Header verification.
* verifying: headers:                    headers_sender_verify.
* verifying: host name:                  Host verification.
* verifying: incoming mail:              Verification of incoming mail.
* verifying: receivers <1>:              receiver_verify.
* verifying: receivers:                  Receiver verification.
* verifying: sender callback <1>:        Sender verification with callback.
* verifying: sender callback:            sender_verify_batch.
* verifying: senders <1>:                sender_verify.
* verifying: senders <2>:                sender_verify_reject.
* verifying: senders <3>:                sender_verify_hosts.
* verifying: senders <4>:                sender_verify_fixup.
* verifying: senders:                    Sender verification.
* VERP:                                  Variable Envelope Return Paths (VERP).
* version number:                        -bV.
* virtual domains:                       Virtual domains.
* VRFY <1>:                              The VRFY and EXPN and DEBUG commands.
* VRFY:                                  smtp_verify.
* warning messages, customizing:         Customizing warning messages.
* warning of delay:                      delay_warning.
* warning of delay, customizing:         warnmsg_file.
* welcome banner for SMTP:               smtp_banner.
* wildcard lookups <1>:                  Partial matching in single-key lookups.
* wildcard lookups <2>:                  Default values in single-key lookups.
* wildcard lookups:                      search_type (domainlist).
* window size:                           Main action buttons.
* X-Failed-Recipients: header:           Delivery in detail.
* X-windows <1>:                         Incorporated code.
* X-windows:                             The Exim monitor.
* X11 libraries:                         Overriding build-time options for Exim.

Function Index
**************

* Menu:

* -<hyphen>:                             -<hyphen>.
* -B<type>:                              -B<type>.
* -bd:                                   -bd.
* -be:                                   -be.
* -bF <filename>:                        -bF <filename>.
* -bf <filename>:                        -bf <filename>.
* -bh <IP address>:                      -bh <IP address>.
* -bi:                                   -bi.
* -bm:                                   -bm.
* -bP:                                   -bP.
* -bp:                                   -bp.
* -bpa:                                  -bpa.
* -bpc:                                  -bpc.
* -bpr:                                  -bpr.
* -bpra:                                 -bpra.
* -bpru:                                 -bpru.
* -bpu:                                  -bpu.
* -brt:                                  -brt.
* -brw:                                  -brw.
* -bs:                                   -bs.
* -bS:                                   -bS.
* -bt:                                   -bt.
* -bv:                                   -bv.
* -bV:                                   -bV.
* -bvs:                                  -bvs.
* -C <filename>:                         -C <filename>.
* -D<macro>=<value>:                     -D<macro>=<value>.
* -d<number>:                            -d<number>.
* -df:                                   -df.
* -dm:                                   -dm.
* -dropcr:                               -dropcr.
* -E:                                    -E.
* -ex:                                   -ex.
* -f <address>:                          -f <address>.
* -F <string>:                           -F <string>.
* -fcntl (exim_lock):                    -fcntl (exim_lock).
* -h <number>:                           -h <number>.
* -h<n>:                                 -h<n>.
* -i:                                    -i.
* -interval (exim_lock):                 -interval (exim_lock).
* -lockfile (exim_lock):                 -lockfile (exim_lock).
* -m:                                    -m.
* -M <message id> <message id>:          -M <message id> <message id>.
* -Mar <message id> <address> <address>: -Mar <message id> <address> <address>.
* -mbx (exim_lock):                      -mbx (exim_lock).
* -Mc <message id> <message id>:         -Mc <message id> <message id>.
* -MC <transport> <hostname> <sequence number> <message id>: -MC <transport> <hostname> <sequence number> <message id>.
* -MCA:                                  -MCA.
* -MCQ <process id> <pipe fd>:           -MCQ <process id> <pipe fd>.
* -MCS:                                  -MCS.
* -MCT:                                  -MCT.
* -Meb <message id>:                     -Meb <message id>.
* -Mes <message id> <address>:           -Mes <message id> <address>.
* -Mf <message id> <message id>:         -Mf <message id> <message id>.
* -Mg <message id> <message id>:         -Mg <message id> <message id>.
* -Mmad <message id> <message id>:       -Mmad <message id> <message id>.
* -Mmd <message id> <address> <address>: -Mmd <message id> <address> <address>.
* -Mrm <message id> <message id>:        -Mrm <message id> <message id>.
* -Mt <message id> <message id>:         -Mt <message id> <message id>.
* -Mvb <message id>:                     -Mvb <message id>.
* -Mvh <message id>:                     -Mvh <message id>.
* -Mvl <message id>:                     -Mvl <message id>.
* -N:                                    -N.
* -n:                                    -n.
* -ne:                                   -ne.
* -nr:                                   -nr.
* -nr/pattern/:                          -nr/pattern/.
* -nt:                                   -nt.
* -oA <file name>:                       -oA <file name>.
* -oB <n>:                               -oB <n>.
* -odb:                                  -odb.
* -odf:                                  -odf.
* -odi:                                  -odi.
* -odq:                                  -odq.
* -odqr:                                 -odqr.
* -odqs:                                 -odqs.
* -oee:                                  -oee.
* -oem:                                  -oem.
* -oep:                                  -oep.
* -oeq:                                  -oeq.
* -oew:                                  -oew.
* -oi:                                   -oi.
* -oitrue:                               -oitrue.
* -om:                                   -om.
* -oMa <host address>:                   -oMa <host address>.
* -oMai <string>:                        -oMai <string>.
* -oMas <address>:                       -oMas <address>.
* -oMi <interface address>:              -oMi <interface address>.
* -oMr <protocol name>:                  -oMr <protocol name>.
* -oMs <host name>:                      -oMs <host name>.
* -oMt <ident string>:                   -oMt <ident string>.
* -oo:                                   -oo.
* -or <time>:                            -or <time>.
* -ov:                                   -ov.
* -oX <number>:                          -oX <number>.
* -pd:                                   -pd.
* -ps:                                   -ps.
* -q:                                    -q.
* -q (exim_lock):                        -q (exim_lock).
* -q <time>:                             -q <time>.
* -q0:                                   -q0.
* -q<n1>:                                -q<n1>.
* -qf:                                   -qf.
* -qff:                                  -qff.
* -qffl:                                 -qffl.
* -qfl:                                  -qfl.
* -ql:                                   -ql.
* -qq:                                   -qq.
* -qR<flags> <string>:                   -qR<flags> <string>.
* -qS<flags> <string>:                   -qS<flags> <string>.
* -r:                                    -r.
* -R<flags> <string>:                    -R<flags> <string>.
* -retries (exim_lock):                  -retries (exim_lock).
* -S<flags> <string>:                    -S<flags> <string>.
* -t:                                    -t.
* -t<n>:                                 -t<n>.
* -timeout (exim_lock):                  -timeout (exim_lock).
* -tnl:                                  -tnl.
* -U:                                    -U.
* -v:                                    -v.
* -v (exim_lock):                        -v (exim_lock).
* -x:                                    -x.
* accept_8bitmime:                       accept_8bitmime.
* accept_timeout:                        accept_timeout.
* admin_groups:                          admin_groups.
* allow_commands (pipe):                 allow_commands (pipe).
* allow_fifo (appendfile):               allow_fifo (appendfile).
* allow_localhost (smtp):                allow_localhost (smtp).
* allow_mx_to_ip:                        allow_mx_to_ip.
* allow_symlink (appendfile):            allow_symlink (appendfile).
* allow_system_actions (forwardfile):    allow_system_actions (forwardfile).
* always_bcc:                            always_bcc.
* auth_always_advertise:                 auth_always_advertise.
* auth_hosts:                            auth_hosts.
* auth_over_tls_hosts:                   auth_over_tls_hosts.
* authenticate_hosts (smtp):             authenticate_hosts (smtp).
* auto_thaw:                             auto_thaw.
* batch (appendfile):                    batch (appendfile).
* batch (lmtp):                          batch (lmtp).
* batch (pipe):                          batch (pipe).
* batch_max (appendfile):                batch_max (appendfile).
* batch_max (lmtp):                      batch_max (lmtp).
* batch_max (pipe):                      batch_max (pipe).
* batch_max (smtp):                      batch_max (smtp).
* bcc (autoreply):                       bcc (autoreply).
* bi_command:                            bi_command.
* body_only (transport):                 body_only (transport).
* bsmtp (appendfile):                    bsmtp (appendfile).
* bsmtp (pipe):                          bsmtp (pipe).
* bsmtp_helo (appendfile):               bsmtp_helo (appendfile).
* bsmtp_helo (pipe):                     bsmtp_helo (pipe).
* cc (autoreply):                        cc (autoreply).
* check_ancestor:                        check_ancestor.
* check_group (appendfile):              check_group (appendfile).
* check_group (forwardfile):             check_group (forwardfile).
* check_local_user (forwardfile):        check_local_user (forwardfile).
* check_log_inodes:                      check_log_inodes.
* check_log_space:                       check_log_space.
* check_owner (appendfile):              check_owner (appendfile).
* check_secondary_mx (lookuphost):       check_secondary_mx (lookuphost).
* check_spool_inodes:                    check_spool_inodes.
* check_spool_space:                     check_spool_space.
* check_string (appendfile):             check_string (appendfile).
* check_string (pipe):                   check_string (pipe).
* client_name (cram_md5):                client_name (cram_md5).
* client_secret (cram_md5):              client_secret (cram_md5).
* client_send (plaintext):               client_send (plaintext).
* collapse_source_routes:                collapse_source_routes.
* command (lmtp):                        command (lmtp).
* command (pipe):                        command (pipe).
* command (queryprogram):                command (queryprogram).
* command_group (queryprogram):          command_group (queryprogram).
* command_timeout (smtp):                command_timeout (smtp).
* command_user (queryprogram):           command_user (queryprogram).
* condition (director or router):        condition (director or router).
* connect_timeout (smtp):                connect_timeout (smtp).
* create_directory (appendfile):         create_directory (appendfile).
* create_file (appendfile):              create_file (appendfile).
* current_directory (appendfile):        current_directory (appendfile).
* current_directory (director):          current_directory (director).
* current_directory (pipe):              current_directory (pipe).
* current_directory (queryprogram):      current_directory (queryprogram).
* daemon_smtp_port:                      daemon_smtp_port.
* daemon_smtp_service:                   daemon_smtp_service.
* data (forwardfile):                    data (forwardfile).
* data_timeout (smtp):                   data_timeout (smtp).
* debug_level:                           debug_level.
* debug_print (director or router):      debug_print (director or router).
* debug_print (transport):               debug_print (transport).
* delay_after_cutoff (smtp):             delay_after_cutoff (smtp).
* delay_warning:                         delay_warning.
* delay_warning_condition:               delay_warning_condition.
* deliver_load_max:                      deliver_load_max.
* deliver_queue_load_max:                deliver_queue_load_max.
* delivery_date_add (transport):         delivery_date_add (transport).
* delivery_date_remove:                  delivery_date_remove.
* directory (appendfile):                directory (appendfile).
* directory2_transport:                  directory2_transport.
* directory2_transport (smartuser):      directory2_transport (smartuser).
* directory_mode (appendfile):           directory_mode (appendfile).
* directory_transport:                   directory_transport.
* directory_transport (smartuser):       directory_transport (smartuser).
* dns_again_means_nonexist:              dns_again_means_nonexist.
* dns_check_names:                       dns_check_names.
* dns_check_names_pattern:               dns_check_names_pattern.
* dns_ipv4_lookup:                       dns_ipv4_lookup.
* dns_qualify_single (smtp):             dns_qualify_single (smtp).
* dns_retrans:                           dns_retrans.
* dns_retry:                             dns_retry.
* dns_search_parents (smtp):             dns_search_parents (smtp).
* domains (director or router):          domains (director or router).
* driver:                                driver.
* driver (director or router):           driver (director or router).
* driver (transport):                    driver (transport).
* envelope_to_add (transport):           envelope_to_add (transport).
* envelope_to_remove:                    envelope_to_remove.
* environment (pipe):                    environment (pipe).
* errmsg_file:                           errmsg_file.
* errmsg_text:                           errmsg_text.
* errors_address:                        errors_address.
* errors_copy:                           errors_copy.
* errors_reply_to:                       errors_reply_to.
* errors_to (director or router):        errors_to (director or router).
* escape_string (appendfile):            escape_string (appendfile).
* escape_string (pipe):                  escape_string (pipe).
* exim_group:                            exim_group.
* exim_path:                             exim_path.
* exim_user:                             exim_user.
* expand (aliasfile):                    expand (aliasfile).
* expn (director):                       expn (director).
* extract_addresses_remove_arguments:    extract_addresses_remove_arguments.
* fail_verify (director or router):      fail_verify (director or router).
* fail_verify_recipient (director or router): fail_verify_recipient (director or router).
* fail_verify_sender (director or router): fail_verify_sender (director or router).
* fallback_hosts (director or router):   fallback_hosts (director or router).
* fallback_hosts (smtp):                 fallback_hosts (smtp).
* file (aliasfile):                      file (aliasfile).
* file (appendfile):                     file (appendfile).
* file (autoreply):                      file (autoreply).
* file (forwardfile):                    file (forwardfile).
* file_directory (forwardfile):          file_directory (forwardfile).
* file_expand (autoreply):               file_expand (autoreply).
* file_format (appendfile):              file_format (appendfile).
* file_must_exist (appendfile):          file_must_exist (appendfile).
* file_optional (autoreply):             file_optional (autoreply).
* file_transport:                        file_transport.
* file_transport (smartuser):            file_transport (smartuser).
* filter (forwardfile):                  filter (forwardfile).
* final_timeout (smtp):                  final_timeout (smtp).
* finduser_retries:                      finduser_retries.
* forbid_domain_literals:                forbid_domain_literals.
* forbid_file:                           forbid_file.
* forbid_file (smartuser):               forbid_file (smartuser).
* forbid_filter_existstest (forwardfile): forbid_filter_existstest (forwardfile).
* forbid_filter_logwrite (forwardfile):  forbid_filter_logwrite (forwardfile).
* forbid_filter_lookup (forwardfile):    forbid_filter_lookup (forwardfile).
* forbid_filter_perl (forwardfile):      forbid_filter_perl (forwardfile).
* forbid_filter_reply (forwardfile):     forbid_filter_reply (forwardfile).
* forbid_include:                        forbid_include.
* forbid_pipe:                           forbid_pipe.
* forbid_pipe (smartuser):               forbid_pipe (smartuser).
* forbid_special (aliasfile):            forbid_special (aliasfile).
* freeze_exec_fail (pipe):               freeze_exec_fail (pipe).
* freeze_missing_include:                freeze_missing_include.
* freeze_tell_mailmaster:                freeze_tell_mailmaster.
* from (autoreply):                      from (autoreply).
* from_hack (appendfile):                from_hack (appendfile).
* from_hack (pipe):                      from_hack (pipe).
* gecos_name:                            gecos_name.
* gecos_pattern:                         gecos_pattern.
* gethostbyname (lookuphost):            gethostbyname (lookuphost).
* gethostbyname (smtp):                  gethostbyname (smtp).
* group (appendfile):                    group (appendfile).
* group (autoreply):                     group (autoreply).
* group (director or router):            group (director or router).
* group (lmtp):                          group (lmtp).
* group (pipe):                          group (pipe).
* headers (autoreply):                   headers (autoreply).
* headers_add (director or router):      headers_add (director or router).
* headers_add (transport):               headers_add (transport).
* headers_check_syntax:                  headers_check_syntax.
* headers_checks_fail:                   headers_checks_fail.
* headers_only (transport):              headers_only (transport).
* headers_remove (director or router):   headers_remove (director or router).
* headers_remove (transport):            headers_remove (transport).
* headers_rewrite (transport):           headers_rewrite (transport).
* headers_sender_verify:                 headers_sender_verify.
* headers_sender_verify_errmsg:          headers_sender_verify_errmsg.
* helo_accept_junk_hosts:                helo_accept_junk_hosts.
* helo_data (smtp):                      helo_data (smtp).
* helo_strict_syntax:                    helo_strict_syntax.
* helo_verify:                           helo_verify.
* hide_child_in_errmsg:                  hide_child_in_errmsg.
* hide_child_in_errmsg (smartuser):      hide_child_in_errmsg (smartuser).
* hold_domains:                          hold_domains.
* home_directory (director):             home_directory (director).
* home_directory (pipe):                 home_directory (pipe).
* host_accept_relay:                     host_accept_relay.
* host_auth_accept_relay:                host_auth_accept_relay.
* host_find_failed (domainlist):         host_find_failed (domainlist).
* host_lookup:                           host_lookup.
* host_reject:                           host_reject.
* host_reject_recipients:                host_reject_recipients.
* hosts (iplookup):                      hosts (iplookup).
* hosts (smtp):                          hosts (smtp).
* hosts_avoid_tls (smtp):                hosts_avoid_tls (smtp).
* hosts_max_try (smtp):                  hosts_max_try (smtp).
* hosts_override (smtp):                 hosts_override (smtp).
* hosts_randomize (domainlist):          hosts_randomize (domainlist).
* hosts_randomize (smtp):                hosts_randomize (smtp).
* hosts_require_tls (smtp):              hosts_require_tls (smtp).
* hosts_treat_as_local:                  hosts_treat_as_local.
* ignore_eacces (forwardfile):           ignore_eacces (forwardfile).
* ignore_enotdir (forwardfile):          ignore_enotdir (forwardfile).
* ignore_errmsg_errors:                  ignore_errmsg_errors.
* ignore_errmsg_errors_after:            ignore_errmsg_errors_after.
* ignore_fromline_hosts:                 ignore_fromline_hosts.
* ignore_fromline_local:                 ignore_fromline_local.
* ignore_status (pipe):                  ignore_status (pipe).
* ignore_target_hosts (router):          ignore_target_hosts (router).
* include_domain (aliasfile):            include_domain (aliasfile).
* initgroups (autoreply):                initgroups (autoreply).
* initgroups (director or router):       initgroups (director or router).
* initgroups (lmtp):                     initgroups (lmtp).
* initgroups (pipe):                     initgroups (pipe).
* interface (smtp):                      interface (smtp).
* keep_malformed:                        keep_malformed.
* keepalive (smtp):                      keepalive (smtp).
* kill_ip_options:                       kill_ip_options.
* ldap_default_servers:                  ldap_default_servers.
* local_domains:                         local_domains.
* local_domains_include_host:            local_domains_include_host.
* local_domains_include_host_literals:   local_domains_include_host_literals.
* local_from_check:                      local_from_check.
* local_from_prefix:                     local_from_prefix.
* local_from_suffix:                     local_from_suffix.
* local_interfaces:                      local_interfaces.
* local_parts (director or router):      local_parts (director or router).
* localhost_number:                      localhost_number.
* locally_caseless:                      locally_caseless.
* lock_fcntl_timeout (appendfile):       lock_fcntl_timeout (appendfile).
* lock_interval (appendfile):            lock_interval (appendfile).
* lock_retries (appendfile):             lock_retries (appendfile).
* lockfile_mode (appendfile):            lockfile_mode (appendfile).
* lockfile_timeout (appendfile):         lockfile_timeout (appendfile).
* log (autoreply):                       log (autoreply).
* log_all_parents:                       log_all_parents.
* log_arguments:                         log_arguments.
* log_defer_output (pipe):               log_defer_output (pipe).
* log_fail_output (pipe):                log_fail_output (pipe).
* log_file_path:                         log_file_path.
* log_incoming_port:                     log_incoming_port.
* log_ip_options:                        log_ip_options.
* log_level:                             log_level.
* log_output (pipe):                     log_output (pipe).
* log_queue_run_level:                   log_queue_run_level.
* log_received_recipients:               log_received_recipients.
* log_received_sender:                   log_received_sender.
* log_refused_recipients:                log_refused_recipients.
* log_rewrites:                          log_rewrites.
* log_sender_on_delivery:                log_sender_on_delivery.
* log_smtp_confirmation:                 log_smtp_confirmation.
* log_smtp_connections:                  log_smtp_connections.
* log_smtp_syntax_errors:                log_smtp_syntax_errors.
* log_subject:                           log_subject.
* lookup_open_max:                       lookup_open_max.
* maildir_format (appendfile):           maildir_format (appendfile).
* maildir_retries (appendfile):          maildir_retries (appendfile).
* maildir_tag (appendfile):              maildir_tag (appendfile).
* mailstore_format (appendfile):         mailstore_format (appendfile).
* mailstore_prefix (appendfile):         mailstore_prefix (appendfile).
* mailstore_suffix (appendfile):         mailstore_suffix (appendfile).
* match_directory (forwardfile):         match_directory (forwardfile).
* match_directory (localuser):           match_directory (localuser).
* max_output (pipe):                     max_output (pipe).
* max_rcpt (smtp):                       max_rcpt (smtp).
* max_username_length:                   max_username_length.
* mbx_format (appendfile):               mbx_format (appendfile).
* message_body_visible:                  message_body_visible.
* message_filter:                        message_filter.
* message_filter_directory2_transport:   message_filter_directory2_transport.
* message_filter_directory_transport:    message_filter_directory_transport.
* message_filter_file_transport:         message_filter_file_transport.
* message_filter_group:                  message_filter_group.
* message_filter_pipe_transport:         message_filter_pipe_transport.
* message_filter_reply_transport:        message_filter_reply_transport.
* message_filter_user:                   message_filter_user.
* message_id_header_text:                message_id_header_text.
* message_size_limit:                    message_size_limit.
* message_size_limit (transport):        message_size_limit (transport).
* message_size_limit_count_recipients:   message_size_limit_count_recipients.
* mode (appendfile):                     mode (appendfile).
* mode (autoreply):                      mode (autoreply).
* mode_fail_narrower (appendfile):       mode_fail_narrower (appendfile).
* modemask:                              modemask.
* modemask (domainlist):                 modemask (domainlist).
* more (director or router):             more (director or router).
* move_frozen_messages:                  move_frozen_messages.
* multi_domain (smtp):                   multi_domain (smtp).
* mx_domains (lookuphost):               mx_domains (lookuphost).
* mx_domains (smtp):                     mx_domains (smtp).
* mysql_servers:                         mysql_servers.
* never_users:                           never_users.
* new_address (smartuser):               new_address (smartuser).
* new_director (director):               new_director (director).
* nobody_group:                          nobody_group.
* nobody_user:                           nobody_user.
* notify_comsat (appendfile):            notify_comsat (appendfile).
* once (autoreply):                      once (autoreply).
* once_file_size (autoreply):            once_file_size (autoreply).
* once_repeat (autoreply):               once_repeat (autoreply).
* one_time:                              one_time.
* optional (aliasfile):                  optional (aliasfile).
* optional (iplookup):                   optional (iplookup).
* owners:                                owners.
* owners (domainlist):                   owners (domainlist).
* owngroups:                             owngroups.
* owngroups (domainlist):                owngroups (domainlist).
* panic_expansion_fail (smartuser):      panic_expansion_fail (smartuser).
* pass_on_timeout (router):              pass_on_timeout (router).
* path (pipe):                           path (pipe).
* percent_hack_domains:                  percent_hack_domains.
* perl_at_start:                         perl_at_start.
* perl_startup:                          perl_startup.
* pgsql_servers:                         pgsql_servers.
* pid_file_path:                         pid_file_path.
* pipe_as_creator (pipe):                pipe_as_creator (pipe).
* pipe_transport:                        pipe_transport.
* pipe_transport (smartuser):            pipe_transport (smartuser).
* port (iplookup):                       port (iplookup).
* port (smtp):                           port (smtp).
* prefix (appendfile):                   prefix (appendfile).
* prefix (director):                     prefix (director).
* prefix (pipe):                         prefix (pipe).
* prefix_optional (director):            prefix_optional (director).
* preserve_message_logs:                 preserve_message_logs.
* primary_hostname:                      primary_hostname.
* print_topbitchars:                     print_topbitchars.
* prod_requires_admin:                   prod_requires_admin.
* prohibition_message:                   prohibition_message.
* protocol (iplookup):                   protocol (iplookup).
* protocol (smtp):                       protocol (smtp).
* public_name:                           public_name.
* qualify_domain:                        qualify_domain.
* qualify_preserve_domain:               qualify_preserve_domain.
* qualify_preserve_domain (smartuser):   qualify_preserve_domain (smartuser).
* qualify_recipient:                     qualify_recipient.
* qualify_single (domainlist):           qualify_single (domainlist).
* qualify_single (lookuphost):           qualify_single (lookuphost).
* queries (aliasfile):                   queries (aliasfile).
* query (aliasfile):                     query (aliasfile).
* query (iplookup):                      query (iplookup).
* queue_list_requires_admin:             queue_list_requires_admin.
* queue_only:                            queue_only.
* queue_only_file:                       queue_only_file.
* queue_only_load:                       queue_only_load.
* queue_remote_domains:                  queue_remote_domains.
* queue_run_in_order:                    queue_run_in_order.
* queue_run_max:                         queue_run_max.
* queue_smtp_domains:                    queue_smtp_domains.
* quota (appendfile):                    quota (appendfile).
* quota_filecount (appendfile):          quota_filecount (appendfile).
* quota_is_inclusive (appendfile):       quota_is_inclusive (appendfile).
* quota_size_regex (appendfile):         quota_size_regex (appendfile).
* quota_warn_message (appendfile):       quota_warn_message (appendfile).
* quota_warn_threshold (appendfile):     quota_warn_threshold (appendfile).
* rbl_domains:                           rbl_domains.
* rbl_hosts:                             rbl_hosts.
* rbl_log_headers:                       rbl_log_headers.
* rbl_log_rcpt_count:                    rbl_log_rcpt_count.
* rbl_reject_recipients:                 rbl_reject_recipients.
* rbl_warn_header:                       rbl_warn_header.
* received_header_text:                  received_header_text.
* received_headers_max:                  received_headers_max.
* receiver_try_verify:                   receiver_try_verify.
* receiver_unqualified_hosts:            receiver_unqualified_hosts.
* receiver_verify:                       receiver_verify.
* receiver_verify_addresses:             receiver_verify_addresses.
* receiver_verify_hosts:                 receiver_verify_hosts.
* receiver_verify_senders:               receiver_verify_senders.
* recipients_max:                        recipients_max.
* recipients_max_reject:                 recipients_max_reject.
* recipients_reject_except:              recipients_reject_except.
* recipients_reject_except_senders:      recipients_reject_except_senders.
* refuse_ip_options:                     refuse_ip_options.
* relay_domains:                         relay_domains.
* relay_domains_include_local_mx:        relay_domains_include_local_mx.
* relay_match_host_or_sender:            relay_match_host_or_sender.
* remote_max_parallel:                   remote_max_parallel.
* remote_sort:                           remote_sort.
* reply_to (autoreply):                  reply_to (autoreply).
* reply_transport (forwardfile):         reply_transport (forwardfile).
* require_files (director or router):    require_files (director or router).
* require_lockfile (appendfile):         require_lockfile (appendfile).
* reroute (iplookup):                    reroute (iplookup).
* response_pattern (iplookup):           response_pattern (iplookup).
* restrict_to_path (pipe):               restrict_to_path (pipe).
* retry_data_expire:                     retry_data_expire.
* retry_include_ip_address (smtp):       retry_include_ip_address (smtp).
* retry_interval_max:                    retry_interval_max.
* retry_use_local_part (appendfile):     retry_use_local_part (appendfile).
* retry_use_local_part (lmtp):           retry_use_local_part (lmtp).
* retry_use_local_part (pipe):           retry_use_local_part (pipe).
* return_fail_output (pipe):             return_fail_output (pipe).
* return_message (autoreply):            return_message (autoreply).
* return_output (pipe):                  return_output (pipe).
* return_path (transport):               return_path (transport).
* return_path_add (transport):           return_path_add (transport).
* return_path_remove:                    return_path_remove.
* return_size_limit:                     return_size_limit.
* rewrite:                               rewrite.
* rewrite (smartuser):                   rewrite (smartuser).
* rewrite_headers (lookuphost):          rewrite_headers (lookuphost).
* rfc1413_hosts:                         rfc1413_hosts.
* rfc1413_query_timeout:                 rfc1413_query_timeout.
* route_file (domainlist):               route_file (domainlist).
* route_list (domainlist):               route_list (domainlist).
* route_queries (domainlist):            route_queries (domainlist).
* route_query (domainlist):              route_query (domainlist).
* search_parents (domainlist):           search_parents (domainlist).
* search_parents (lookuphost):           search_parents (lookuphost).
* search_type (aliasfile):               search_type (aliasfile).
* search_type (domainlist):              search_type (domainlist).
* security:                              security.
* self (router):                         self (router).
* sender_address_relay:                  sender_address_relay.
* sender_address_relay_hosts:            sender_address_relay_hosts.
* sender_reject:                         sender_reject.
* sender_reject_recipients:              sender_reject_recipients.
* sender_try_verify:                     sender_try_verify.
* sender_unqualified_hosts:              sender_unqualified_hosts.
* sender_verify:                         sender_verify.
* sender_verify_batch:                   sender_verify_batch.
* sender_verify_callback_domains:        sender_verify_callback_domains.
* sender_verify_callback_timeout:        sender_verify_callback_timeout.
* sender_verify_fixup:                   sender_verify_fixup.
* sender_verify_hosts:                   sender_verify_hosts.
* sender_verify_hosts_callback:          sender_verify_hosts_callback.
* sender_verify_max_retry_rate:          sender_verify_max_retry_rate.
* sender_verify_reject:                  sender_verify_reject.
* senders (director or router):          senders (director or router).
* serialize_hosts (smtp):                serialize_hosts (smtp).
* server_condition (plaintext):          server_condition (plaintext).
* server_mail_auth_condition:            server_mail_auth_condition.
* server_prompts (plaintext):            server_prompts (plaintext).
* server_secret (cram_md5):              server_secret (cram_md5).
* server_set_id:                         server_set_id.
* service (iplookup):                    service (iplookup).
* service (smtp):                        service (smtp).
* seteuid (forwardfile):                 seteuid (forwardfile).
* shadow_condition (transport):          shadow_condition (transport).
* shadow_transport (transport):          shadow_transport (transport).
* size_addition (smtp):                  size_addition (smtp).
* skip_syntax_errors:                    skip_syntax_errors.
* smtp_accept_keepalive:                 smtp_accept_keepalive.
* smtp_accept_max:                       smtp_accept_max.
* smtp_accept_max_per_host:              smtp_accept_max_per_host.
* smtp_accept_queue:                     smtp_accept_queue.
* smtp_accept_queue_per_connection:      smtp_accept_queue_per_connection.
* smtp_accept_reserve:                   smtp_accept_reserve.
* smtp_banner:                           smtp_banner.
* smtp_check_spool_space:                smtp_check_spool_space.
* smtp_connect_backlog:                  smtp_connect_backlog.
* smtp_etrn_command:                     smtp_etrn_command.
* smtp_etrn_hosts:                       smtp_etrn_hosts.
* smtp_etrn_serialize:                   smtp_etrn_serialize.
* smtp_expn_hosts:                       smtp_expn_hosts.
* smtp_load_reserve:                     smtp_load_reserve.
* smtp_receive_timeout:                  smtp_receive_timeout.
* smtp_reserve_hosts:                    smtp_reserve_hosts.
* smtp_verify:                           smtp_verify.
* split_spool_directory:                 split_spool_directory.
* spool_directory:                       spool_directory.
* strip_excess_angle_brackets:           strip_excess_angle_brackets.
* strip_trailing_dot:                    strip_trailing_dot.
* subject (autoreply):                   subject (autoreply).
* suffix (appendfile):                   suffix (appendfile).
* suffix (director):                     suffix (director).
* suffix (pipe):                         suffix (pipe).
* suffix_optional (director):            suffix_optional (director).
* syntax_errors_text:                    syntax_errors_text.
* syntax_errors_to:                      syntax_errors_to.
* syslog_timestamp:                      syslog_timestamp.
* temp_errors (pipe):                    temp_errors (pipe).
* text (autoreply):                      text (autoreply).
* timeout (iplookup):                    timeout (iplookup).
* timeout (lmtp):                        timeout (lmtp).
* timeout (pipe):                        timeout (pipe).
* timeout (queryprogram):                timeout (queryprogram).
* timeout_frozen_after:                  timeout_frozen_after.
* timestamps_utc:                        timestamps_utc.
* timezone:                              timezone.
* tls_advertise_hosts:                   tls_advertise_hosts.
* tls_certificate:                       tls_certificate.
* tls_certificate (smtp):                tls_certificate (smtp).
* tls_dhparam:                           tls_dhparam.
* tls_host_accept_relay:                 tls_host_accept_relay.
* tls_hosts:                             tls_hosts.
* tls_log_cipher:                        tls_log_cipher.
* tls_log_peerdn:                        tls_log_peerdn.
* tls_privatekey:                        tls_privatekey.
* tls_privatekey (smtp):                 tls_privatekey (smtp).
* tls_verify_certificates:               tls_verify_certificates.
* tls_verify_certificates (smtp):        tls_verify_certificates (smtp).
* tls_verify_ciphers:                    tls_verify_ciphers.
* tls_verify_ciphers (smtp):             tls_verify_ciphers (smtp).
* tls_verify_hosts:                      tls_verify_hosts.
* to (autoreply):                        to (autoreply).
* translate_ip_address (router):         translate_ip_address (router).
* transport (director or router):        transport (director or router).
* transport_filter (transport):          transport_filter (transport).
* trusted_groups:                        trusted_groups.
* trusted_users:                         trusted_users.
* umask (pipe):                          umask (pipe).
* unknown_login:                         unknown_login.
* unknown_username:                      unknown_username.
* unseen (director or router):           unseen (director or router).
* untrusted_set_sender:                  untrusted_set_sender.
* use_crlf (appendfile):                 use_crlf (appendfile).
* use_crlf (pipe):                       use_crlf (pipe).
* use_fcntl_lock (appendfile):           use_fcntl_lock (appendfile).
* use_lockfile (appendfile):             use_lockfile (appendfile).
* use_mbx_lock (appendfile):             use_mbx_lock (appendfile).
* use_shell (pipe):                      use_shell (pipe).
* user (appendfile):                     user (appendfile).
* user (autoreply):                      user (autoreply).
* user (director or router):             user (director or router).
* user (lmtp):                           user (lmtp).
* user (pipe):                           user (pipe).
* uucp_from_pattern:                     uucp_from_pattern.
* uucp_from_sender:                      uucp_from_sender.
* verify (director or router):           verify (director or router).
* verify_only (director or router):      verify_only (director or router).
* verify_recipient (director or router): verify_recipient (director or router).
* verify_sender (director or router):    verify_sender (director or router).
* warnmsg_file:                          warnmsg_file.
* widen_domains (lookuphost):            widen_domains (lookuphost).



Tag Table:
Node: Top79
Node: Introduction3729
Node: Web site and Mailing list7493
Node: Availability8713
Node: Limitations10901
Node: Features13444
Node: Support for IPv618992
Node: Calling interface20023
Node: Terminology21960
Node: Incorporated code24969
Node: How Exim delivers mail28388
Node: Philosophy28696
Node: Message reception29295
Node: Life of a message33587
Node: Drivers36274
Node: Delivery in detail39881
Node: Temporary delivery failures48459
Node: Building and installing Exim50293
Node: Unpacking51054
Node: Multiple machine architectures and operating systems52368
Node: DBM libraries53197
Node: Pre-building configuration56062
Node: Including TLS/SSL encryption support58191
Node: Use of tcpwrappers59098
Node: Including support for IPv660408
Node: The building process60910
Node: Overriding build-time options for Exim62291
Node: OS-specific header files68576
Node: Overriding build-time options for the monitor69152
Node: Installing commands and scripts70117
Node: Installing info documentation72292
Node: Setting up the spool directory73008
Node: Testing73489
Node: Switching Exim on76575
Node: Exim on heavily loaded hosts77836
Node: Stopping Exim on Solaris78402
Node: The Exim command line79632
Node: Setting options by program name80349
Node: Trusted and admin users81848
Node: Command line options84667
Node: -<hyphen>86480
Node: -B<type>86977
Node: -bd87225
Node: -be88971
Node: -bF <filename>89620
Node: -bf <filename>89959
Node: -bh <IP address>91612
Node: -bi92615
Node: -bm93507
Node: -bp94856
Node: -bpa96519
Node: -bpc96879
Node: -bpr97177
Node: -bpra97576
Node: -bpru97742
Node: -bpu97908
Node: -bP98284
Node: -brt99966
Node: -brw100990
Node: -bS101450
Node: -bs102759
Node: -bt103740
Node: -bV105076
Node: -bv105306
Node: -bvs107080
Node: -C <filename>107364
Node: -D<macro>=<value>108339
Node: -d<number>108846
Node: -df109748
Node: -dm110138
Node: -dropcr110372
Node: -E110950
Node: -ex111584
Node: -F <string>111978
Node: -f <address>112455
Node: -h <number>113878
Node: -i114192
Node: -M <message id> <message id>114589
Node: -Mar <message id> <address> <address>115404
Node: -MC <transport> <hostname> <sequence number> <message id>116025
Node: -MCA116700
Node: -MCQ <process id> <pipe fd>117086
Node: -MCS117688
Node: -MCT118058
Node: -Mc <message id> <message id>118406
Node: -Meb <message id>119399
Node: -Mes <message id> <address>120350
Node: -Mf <message id> <message id>120977
Node: -Mg <message id> <message id>121565
Node: -Mmad <message id> <message id>122095
Node: -Mmd <message id> <address> <address>122606
Node: -Mrm <message id> <message id>123190
Node: -Mt <message id> <message id>123705
Node: -Mvb <message id>124155
Node: -Mvh <message id>124479
Node: -Mvl <message id>124794
Node: -m125086
Node: -N125305
Node: -n126367
Node: -oA <file name>126570
Node: -oB <n>126875
Node: -odb127228
Node: -odf127785
Node: -odi128377
Node: -odq128577
Node: -odqr129084
Node: -odqs129653
Node: -oee130411
Node: -oem130928
Node: -oep131251
Node: -oeq131514
Node: -oew131720
Node: -oi131925
Node: -oitrue132229
Node: -oMa <host address>132414
Node: -oMas <address>133205
Node: -oMai <string>133762
Node: -oMi <interface address>134281
Node: -oMr <protocol name>134853
Node: -oMs <host name>135422
Node: -oMt <ident string>135925
Node: -om136546
Node: -oo136886
Node: -or <time>137094
Node: -ov137551
Node: -oX <number>137724
Node: -pd138256
Node: -ps138610
Node: -q138957
Node: -q <time>141360
Node: -qf142541
Node: -qff142912
Node: -qfl143210
Node: -qffl143611
Node: -ql143936
Node: -qq144379
Node: -qR<flags> <string>145350
Node: -qS<flags> <string>145602
Node: -R<flags> <string>145826
Node: -r147781
Node: -S<flags> <string>147988
Node: -t148428
Node: -U149706
Node: -v150055
Node: -x150393
Node: File and database lookups150720
Node: Single-key lookup types152097
Node: An lsearch file is not an item list155269
Node: Query-style lookup types156655
Node: Use of data lookups158148
Node: Temporary errors in lookups160751
Node: Default values in single-key lookups162349
Node: Partial matching in single-key lookups163370
Node: Lookup caching166574
Node: Quoting lookup data167448
Node: More about NIS+168640
Node: More about LDAP169683
Node: More about MySQL and PostgreSQL176325
Node: More about dnsdb178675
Node: The Exim configuration file179721
Node: Configuration file format182382
Node: Macros in the configuration file185158
Node: Common option syntax187264
Node: Integer188870
Node: Octal integer189579
Node: Fixed point number189899
Node: Time interval190186
Node: String190678
Node: Expanded strings192407
Node: User and group names193134
Node: List construction194040
Node: Domain lists195593
Node: Host lists203607
Node: Mixing host names and addresses in host lists211108
Node: Use of RFC 1413 identification in host lists212105
Node: Address lists212921
Node: Case of letters in address lists218813
Node: Regular expressions220535
Node: Testing regular expressions221474
Node: String expansions222972
Node: Testing string expansions224713
Node: Expansion items225660
Node: Expansion operators238222
Node: Expansion conditions246150
Node: Expansion variables254914
Node: Embedded Perl279253
Node: Main configuration283155
Node: accept_8bitmime289007
Node: accept_timeout289545
Node: admin_groups290055
Node: allow_mx_to_ip290682
Node: always_bcc291324
Node: auth_always_advertise291959
Node: auth_hosts293284
Node: auth_over_tls_hosts293771
Node: auto_thaw294212
Node: bi_command294816
Node: check_log_inodes295280
Node: check_log_space295503
Node: check_spool_inodes295732
Node: check_spool_space295968
Node: collapse_source_routes297429
Node: daemon_smtp_port297866
Node: daemon_smtp_service298319
Node: debug_level298574
Node: delay_warning298909
Node: delay_warning_condition299748
Node: deliver_load_max300728
Node: deliver_queue_load_max301358
Node: delivery_date_remove301717
Node: dns_again_means_nonexist302372
Node: dns_check_names303082
Node: dns_check_names_pattern303677
Node: dns_retrans304217
Node: dns_ipv4_lookup305021
Node: dns_retry305965
Node: envelope_to_remove306169
Node: errmsg_text306833
Node: errmsg_file307223
Node: errors_address307685
Node: errors_copy308765
Node: errors_reply_to310442
Node: exim_group311016
Node: exim_path311552
Node: exim_user312029
Node: extract_addresses_remove_arguments313076
Node: finduser_retries313810
Node: forbid_domain_literals314500
Node: freeze_tell_mailmaster315020
Node: gecos_name315770
Node: gecos_pattern316988
Node: headers_check_syntax317203
Node: headers_checks_fail318033
Node: headers_sender_verify318416
Node: headers_sender_verify_errmsg319602
Node: helo_accept_junk_hosts320082
Node: helo_strict_syntax320556
Node: helo_verify321068
Node: hold_domains322124
Node: host_accept_relay323113
Node: host_auth_accept_relay323555
Node: host_lookup324120
Node: host_reject324976
Node: host_reject_recipients325407
Node: hosts_treat_as_local325970
Node: ignore_errmsg_errors326845
Node: ignore_errmsg_errors_after327283
Node: ignore_fromline_hosts328312
Node: ignore_fromline_local329059
Node: keep_malformed329315
Node: kill_ip_options329745
Node: ldap_default_servers330836
Node: local_domains331308
Node: local_domains_include_host332590
Node: local_domains_include_host_literals333186
Node: local_from_check333855
Node: local_from_prefix334491
Node: local_from_suffix335422
Node: local_interfaces335659
Node: localhost_number337001
Node: locally_caseless338137
Node: log_all_parents339377
Node: log_arguments340381
Node: log_file_path341132
Node: log_incoming_port342001
Node: log_ip_options342631
Node: log_level342850
Node: log_queue_run_level343289
Node: log_received_recipients343667
Node: log_received_sender344228
Node: log_refused_recipients344681
Node: log_rewrites345129
Node: log_sender_on_delivery345428
Node: log_smtp_confirmation345884
Node: log_smtp_connections346484
Node: log_smtp_syntax_errors347219
Node: log_subject347738
Node: lookup_open_max348097
Node: max_username_length348924
Node: message_body_visible349419
Node: message_filter349744
Node: message_filter_directory_transport350394
Node: message_filter_directory2_transport350886
Node: message_filter_file_transport351513
Node: message_filter_group351926
Node: message_filter_pipe_transport352826
Node: message_filter_reply_transport353207
Node: message_filter_user353587
Node: message_id_header_text354404
Node: message_size_limit355387
Node: message_size_limit_count_recipients356237
Node: move_frozen_messages356816
Node: mysql_servers357497
Node: never_users357978
Node: nobody_group358680
Node: nobody_user359005
Node: percent_hack_domains359420
Node: perl_at_start360344
Node: perl_startup360674
Node: pgsql_servers360994
Node: pid_file_path361480
Node: preserve_message_logs362223
Node: primary_hostname362775
Node: print_topbitchars363371
Node: prod_requires_admin363971
Node: prohibition_message364346
Node: qualify_domain364837
Node: qualify_recipient365556
Node: queue_list_requires_admin366229
Node: queue_only366668
Node: queue_only_file367271
Node: queue_only_load368054
Node: queue_remote_domains368811
Node: queue_run_in_order369567
Node: queue_run_max370427
Node: queue_smtp_domains371141
Node: rbl_domains372256
Node: rbl_hosts372761
Node: rbl_log_headers373191
Node: rbl_log_rcpt_count373643
Node: rbl_reject_recipients374105
Node: rbl_warn_header374498
Node: received_header_text375023
Node: received_headers_max376849
Node: receiver_try_verify377547
Node: receiver_unqualified_hosts377796
Node: receiver_verify378637
Node: receiver_verify_addresses379539
Node: receiver_verify_hosts379944
Node: receiver_verify_senders380205
Node: recipients_max381066
Node: recipients_max_reject381748
Node: recipients_reject_except382393
Node: recipients_reject_except_senders382931
Node: refuse_ip_options383404
Node: relay_domains383651
Node: relay_domains_include_local_mx384053
Node: relay_match_host_or_sender384637
Node: remote_max_parallel385425
Node: remote_sort388224
Node: retry_data_expire388721
Node: retry_interval_max389165
Node: return_path_remove389613
Node: return_size_limit390349
Node: rfc1413_hosts391184
Node: rfc1413_query_timeout391537
Node: security391850
Node: sender_address_relay392808
Node: sender_address_relay_hosts394391
Node: sender_reject395013
Node: sender_reject_recipients396102
Node: sender_try_verify396736
Node: sender_unqualified_hosts396979
Node: sender_verify397788
Node: sender_verify_batch398791
Node: sender_verify_callback_domains399106
Node: sender_verify_callback_timeout399759
Node: sender_verify_fixup400083
Node: sender_verify_hosts400963
Node: sender_verify_hosts_callback401491
Node: sender_verify_max_retry_rate401791
Node: sender_verify_reject402905
Node: smtp_accept_keepalive403344
Node: smtp_accept_max403962
Node: smtp_accept_max_per_host404535
Node: smtp_accept_queue405119
Node: smtp_accept_queue_per_connection405807
Node: smtp_accept_reserve406733
Node: smtp_banner407402
Node: smtp_check_spool_space408186
Node: smtp_connect_backlog408774
Node: smtp_etrn_command409644
Node: smtp_etrn_hosts410908
Node: smtp_etrn_serialize411271
Node: smtp_expn_hosts411706
Node: smtp_load_reserve412407
Node: smtp_receive_timeout413018
Node: smtp_reserve_hosts413508
Node: smtp_verify413842
Node: split_spool_directory414147
Node: spool_directory415989
Node: strip_excess_angle_brackets416985
Node: strip_trailing_dot417592
Node: syslog_timestamp418076
Node: timeout_frozen_after418459
Node: timestamps_utc419156
Node: timezone419528
Node: tls_advertise_hosts420363
Node: tls_certificate420862
Node: tls_dhparam421193
Node: tls_host_accept_relay421526
Node: tls_hosts421868
Node: tls_log_cipher422193
Node: tls_log_peerdn422534
Node: tls_privatekey423029
Node: tls_verify_certificates423364
Node: tls_verify_ciphers423772
Node: tls_verify_hosts424272
Node: trusted_groups424740
Node: trusted_users425308
Node: unknown_login425818
Node: unknown_username426479
Node: untrusted_set_sender426703
Node: uucp_from_pattern427807
Node: uucp_from_sender429079
Node: warnmsg_file429318
Node: Driver specifications429839
Node: Environment for running local transports433973
Node: Uids and gids435299
Node: Current and home directories437893
Node: Expansion variables derived from the address439920
Node: Generic options for transports440653
Node: body_only (transport)441387
Node: debug_print (transport)441921
Node: delivery_date_add (transport)442638
Node: driver (transport)443237
Node: envelope_to_add (transport)443656
Node: headers_add (transport)444482
Node: headers_only (transport)445947
Node: headers_remove (transport)446479
Node: headers_rewrite (transport)447552
Node: message_size_limit (transport)448925
Node: return_path (transport)449628
Node: return_path_add (transport)450299
Node: shadow_condition (transport)451221
Node: shadow_transport (transport)451534
Node: transport_filter (transport)453128
Node: The appendfile transport456459
Node: Private options for appendfile459332
Node: allow_fifo (appendfile)461076
Node: allow_symlink (appendfile)461509
Node: batch (appendfile)462141
Node: batch_max (appendfile)463361
Node: bsmtp (appendfile)463721
Node: bsmtp_helo (appendfile)464776
Node: check_group (appendfile)465202
Node: check_owner (appendfile)465714
Node: check_string (appendfile)466113
Node: create_directory (appendfile)467454
Node: create_file (appendfile)467904
Node: current_directory (appendfile)468739
Node: directory (appendfile)469280
Node: directory_mode (appendfile)469986
Node: escape_string (appendfile)470381
Node: file (appendfile)470666
Node: file_format (appendfile)472295
Node: file_must_exist (appendfile)473687
Node: from_hack (appendfile)474111
Node: group (appendfile)474629
Node: lock_fcntl_timeout (appendfile)475934
Node: lock_interval (appendfile)477637
Node: lock_retries (appendfile)478001
Node: lockfile_mode (appendfile)478391
Node: lockfile_timeout (appendfile)478766
Node: maildir_format (appendfile)479233
Node: maildir_retries (appendfile)479825
Node: maildir_tag (appendfile)480252
Node: mailstore_format (appendfile)480667
Node: mailstore_prefix (appendfile)481222
Node: mailstore_suffix (appendfile)481655
Node: mbx_format (appendfile)482082
Node: mode (appendfile)483688
Node: mode_fail_narrower (appendfile)484350
Node: notify_comsat (appendfile)484921
Node: prefix (appendfile)485361
Node: quota (appendfile)485986
Node: quota_filecount (appendfile)488452
Node: quota_is_inclusive (appendfile)488913
Node: quota_size_regex (appendfile)489216
Node: quota_warn_message (appendfile)490270
Node: quota_warn_threshold (appendfile)490991
Node: require_lockfile (appendfile)492203
Node: retry_use_local_part (appendfile)493011
Node: suffix (appendfile)493845
Node: use_crlf (appendfile)494371
Node: use_fcntl_lock (appendfile)495200
Node: use_lockfile (appendfile)495845
Node: use_mbx_lock (appendfile)496947
Node: user (appendfile)497775
Node: Operational details for appending498671
Node: Operational details for delivery to a new file505255
Node: The autoreply transport510893
Node: Private options for autoreply513939
Node: bcc (autoreply)514605
Node: cc (autoreply)514989
Node: file (autoreply)515350
Node: file_expand (autoreply)515775
Node: file_optional (autoreply)516155
Node: from (autoreply)516522
Node: group (autoreply)516862
Node: headers (autoreply)517581
Node: initgroups (autoreply)518051
Node: log (autoreply)518533
Node: mode (autoreply)518935
Node: once (autoreply)519233
Node: once_file_size (autoreply)520717
Node: once_repeat (autoreply)520982
Node: reply_to (autoreply)521243
Node: return_message (autoreply)521616
Node: subject (autoreply)522037
Node: text (autoreply)522389
Node: to (autoreply)522811
Node: user (autoreply)523173
Node: The lmtp transport523963
Node: batch (lmtp)524920
Node: batch_max (lmtp)525852
Node: command (lmtp)526115
Node: group (lmtp)526716
Node: initgroups (lmtp)527405
Node: retry_use_local_part (lmtp)527866
Node: timeout (lmtp)528653
Node: user (lmtp)528970
Node: The lmtp transport (continued)529773
Node: The pipe transport530180
Node: Returned status and data531633
Node: How the command is run532885
Node: Environment variables536259
Node: Private options for pipe537958
Node: allow_commands (pipe)538946
Node: batch (pipe)540043
Node: batch_max (pipe)541234
Node: bsmtp (pipe)541558
Node: bsmtp_helo (pipe)542534
Node: check_string (pipe)542925
Node: command (pipe)543689
Node: current_directory (pipe)544363
Node: environment (pipe)544961
Node: escape_string (pipe)545492
Node: freeze_exec_fail (pipe)545747
Node: from_hack (pipe)546256
Node: group (pipe)546624
Node: home_directory (pipe)547325
Node: ignore_status (pipe)547950
Node: initgroups (pipe)548501
Node: log_defer_output (pipe)548960
Node: log_fail_output (pipe)549415
Node: log_output (pipe)549900
Node: max_output (pipe)550256
Node: path (pipe)550909
Node: pipe_as_creator (pipe)551347
Node: prefix (pipe)552115
Node: restrict_to_path (pipe)552885
Node: retry_use_local_part (pipe)553485
Node: return_fail_output (pipe)554295
Node: return_output (pipe)554911
Node: suffix (pipe)555546
Node: temp_errors (pipe)556010
Node: timeout (pipe)556656
Node: umask (pipe)557270
Node: use_crlf (pipe)557543
Node: use_shell (pipe)558330
Node: user (pipe)559060
Node: Using an external local delivery agent559832
Node: The smtp transport562286
Node: allow_localhost (smtp)563709
Node: authenticate_hosts (smtp)564368
Node: batch_max (smtp)564928
Node: command_timeout (smtp)565923
Node: connect_timeout (smtp)566339
Node: data_timeout (smtp)566995
Node: delay_after_cutoff (smtp)567444
Node: dns_qualify_single (smtp)568864
Node: dns_search_parents (smtp)569306
Node: fallback_hosts (smtp)569923
Node: final_timeout (smtp)571703
Node: gethostbyname (smtp)572079
Node: helo_data (smtp)572639
Node: hosts (smtp)572996
Node: hosts_avoid_tls (smtp)574590
Node: hosts_require_tls (smtp)574985
Node: hosts_override (smtp)575392
Node: hosts_max_try (smtp)575856
Node: hosts_randomize (smtp)576629
Node: interface (smtp)577033
Node: keepalive (smtp)577664
Node: max_rcpt (smtp)578177
Node: multi_domain (smtp)578619
Node: mx_domains (smtp)579251
Node: port (smtp)579711
Node: protocol (smtp)580182
Node: retry_include_ip_address (smtp)580762
Node: serialize_hosts (smtp)581735
Node: service (smtp)583106
Node: size_addition (smtp)583361
Node: tls_certificate (smtp)584122
Node: tls_privatekey (smtp)584727
Node: tls_verify_certificates (smtp)585340
Node: tls_verify_ciphers (smtp)585978
Node: Generic options common to both directors and routers586520
Node: condition (director or router)588024
Node: debug_print (director or router)589027
Node: domains (director or router)589923
Node: driver (director or router)591467
Node: errors_to (director or router)591866
Node: fail_verify (director or router)592848
Node: fail_verify_recipient (director or router)593292
Node: fail_verify_sender (director or router)593828
Node: fallback_hosts (director or router)594355
Node: group (director or router)595043
Node: headers_add (director or router)596055
Node: headers_remove (director or router)597743
Node: initgroups (director or router)598591
Node: local_parts (director or router)599311
Node: more (director or router)600982
Node: require_files (director or router)601755
Node: senders (director or router)605405
Node: transport (director or router)606715
Node: unseen (director or router)607647
Node: user (director or router)608385
Node: verify (director or router)609494
Node: verify_only (director or router)609892
Node: verify_recipient (director or router)610580
Node: verify_sender (director or router)611121
Node: Skipping directors and routers611651
Node: Additional generic options for directors615116
Node: current_directory (director)616036
Node: expn (director)617031
Node: home_directory (director)617935
Node: new_director (director)619069
Node: prefix (director)620007
Node: prefix_optional (director)621822
Node: suffix (director)622099
Node: suffix_optional (director)622785
Node: Skipping directors623063
Node: Options common to the aliasfile and forwardfile directors624621
Node: check_ancestor625805
Node: directory_transport627389
Node: directory2_transport627920
Node: file_transport628469
Node: forbid_file628978
Node: forbid_include629377
Node: forbid_pipe629768
Node: freeze_missing_include630156
Node: hide_child_in_errmsg630656
Node: modemask631252
Node: one_time631717
Node: owners633283
Node: owngroups633965
Node: pipe_transport634754
Node: qualify_preserve_domain635278
Node: rewrite635719
Node: skip_syntax_errors636093
Node: syntax_errors_text637073
Node: syntax_errors_to637356
Node: The aliasfile director638019
Node: Specifying a transport for aliasfile639715
Node: Alias file format640929
Node: Types of alias item643195
Node: Duplicate addresses650215
Node: Repeated alias expansion651178
Node: Errors in alias files651772
Node: Aliasfile private options652449
Node: expand (aliasfile)653036
Node: file (aliasfile)653528
Node: forbid_special (aliasfile)654395
Node: include_domain (aliasfile)654798
Node: optional (aliasfile)655643
Node: queries (aliasfile)656352
Node: query (aliasfile)656947
Node: search_type (aliasfile)657866
Node: The forwardfile director658912
Node: Forward file items660317
Node: Repeated forwarding expansion666972
Node: Errors in forward files667594
Node: Filter files668332
Node: The home directory669216
Node: Special treatment of home_directory and current_directory670814
Node: Forwardfile private options672332
Node: allow_system_actions (forwardfile)673323
Node: check_group (forwardfile)673942
Node: check_local_user (forwardfile)674420
Node: data (forwardfile)675475
Node: file (forwardfile)676629
Node: file_directory (forwardfile)678476
Node: filter (forwardfile)679892
Node: forbid_filter_existstest (forwardfile)681635
Node: forbid_filter_logwrite (forwardfile)682050
Node: forbid_filter_lookup (forwardfile)682643
Node: forbid_filter_perl (forwardfile)683050
Node: forbid_filter_reply (forwardfile)683527
Node: ignore_eacces (forwardfile)684047
Node: ignore_enotdir (forwardfile)684484
Node: match_directory (forwardfile)684943
Node: reply_transport (forwardfile)686239
Node: seteuid (forwardfile)686768
Node: The localuser director688591
Node: match_directory (localuser)690034
Node: The localuser director (continued)691365
Node: The smartuser director691784
Node: directory_transport (smartuser)693538
Node: directory2_transport (smartuser)694071
Node: file_transport (smartuser)694627
Node: forbid_file (smartuser)695143
Node: forbid_pipe (smartuser)695564
Node: hide_child_in_errmsg (smartuser)695972
Node: new_address (smartuser)696585
Node: panic_expansion_fail (smartuser)698094
Node: pipe_transport (smartuser)698390
Node: qualify_preserve_domain (smartuser)698932
Node: rewrite (smartuser)699413
Node: Additional generic options for routers699718
Node: ignore_target_hosts (router)700378
Node: pass_on_timeout (router)701395
Node: self (router)702184
Node: translate_ip_address (router)705542
Node: The domainlist router707114
Node: host_find_failed (domainlist)709134
Node: hosts_randomize (domainlist)710215
Node: modemask (domainlist)711704
Node: owners (domainlist)712077
Node: owngroups (domainlist)712516
Node: qualify_single (domainlist)712962
Node: route_file (domainlist)713523
Node: route_list (domainlist)714155
Node: route_queries (domainlist)714722
Node: route_query (domainlist)715355
Node: search_parents (domainlist)716000
Node: search_type (domainlist)716698
Node: Routing rules718488
Node: Host list format720984
Node: Options format722486
Node: Application of routing rules723672
Node: Domainlist examples726790
Node: The ipliteral router733512
Node: The iplookup router734282
Node: hosts (iplookup)736174
Node: optional (iplookup)736568
Node: port (iplookup)736975
Node: protocol (iplookup)737262
Node: query (iplookup)737567
Node: reroute (iplookup)738036
Node: response_pattern (iplookup)738757
Node: service (iplookup)739617
Node: timeout (iplookup)739887
Node: The lookuphost router740247
Node: check_secondary_mx (lookuphost)741550
Node: gethostbyname (lookuphost)742074
Node: mx_domains (lookuphost)742812
Node: qualify_single (lookuphost)743662
Node: rewrite_headers (lookuphost)744325
Node: search_parents (lookuphost)745551
Node: widen_domains (lookuphost)746536
Node: The queryprogram router747357
Node: command (queryprogram)748177
Node: command_group (queryprogram)748645
Node: command_user (queryprogram)749094
Node: current_directory (queryprogram)749649
Node: timeout (queryprogram)750055
Node: The queryprogram router (continued)750470
Node: Retry configuration753503
Node: Retry rules756001
Node: Retry rule examples762853
Node: Timeout of retry data764800
Node: Long-term failures765907
Node: Ultimate address timeout768492
Node: Address rewriting769406
Node: Testing the rewriting rules that apply on input773932
Node: Rewriting rules775184
Node: Rewriting patterns777167
Node: Rewriting replacements781282
Node: Rewriting flags782418
Node: Flags specifying which headers and envelope addresses to rewrite783098
Node: The SMTP-time rewriting flag784326
Node: Flags controlling the rewriting process785373
Node: The additional relay checking flag787531
Node: Rewriting examples788906
Node: SMTP authentication791498
Node: Generic options for authenticators796324
Node: driver796640
Node: public_name796939
Node: server_set_id797810
Node: server_mail_auth_condition798465
Node: Authentication on an Exim server799342
Node: Testing server authentication802026
Node: Authenticated senders803486
Node: Authentication by an Exim client804263
Node: The plaintext authenticator806217
Node: Using plaintext in a server807039
Node: server_prompts (plaintext)807470
Node: server_condition (plaintext)807807
Node: Using plaintext in a server (continued)808147
Node: Using plaintext in a client811697
Node: client_send (plaintext)812038
Node: Using plaintext in a client (continued)812866
Node: The cram_md5 authenticator813659
Node: Using cram_md5 as a server814442
Node: server_secret (cram_md5)814812
Node: Using cram_md5 as a server (continued)815515
Node: Using cram_md5 as a client816235
Node: client_name (cram_md5)816609
Node: client_secret (cram_md5)817005
Node: Using cram_md5 as a client (continued)817389
Node: Encrypted SMTP connections using TLS/SSL818155
Node: Configuring Exim to use TLS as a server819371
Node: Configuring Exim to use TLS as a client825909
Node: Multiple messages on the same TCP/IP connection828125
Node: Certificates and all that829370
Node: Customizing error and warning messages830962
Node: Customizing error messages831667
Node: Customizing warning messages834789
Node: The default configuration file837059
Node: Main configuration settings837773
Node: Transport configuration settings839335
Node: Director configuration settings841507
Node: Router configuration settings843516
Node: Default retry rule844038
Node: Rewriting configuration844560
Node: Authenticators configuration844826
Node: Multiple user mailboxes845200
Node: Using Exim to handle mailing lists846939
Node: Syntax errors in mailing lists849543
Node: NFS-mounted mailing lists850268
Node: Re-expansion of mailing lists850986
Node: Closed mailing lists852679
Node: Virtual domains854495
Node: All mail to a given host854998
Node: Virtual domains not preserving envelopes855769
Node: Virtual domains preserving envelopes857451
Node: Intermittently connected hosts859033
Node: Exim on the upstream host859823
Node: Exim on the intermittently connected host861285
Node: Handling many intermittently connected hosts862500
Node: Verification of incoming mail863751
Node: Host verification864619
Node: Sender verification867408
Node: Sender verification with callback872976
Node: Fixing bad senders875196
Node: Header verification876578
Node: Receiver verification878920
Node: Other policy controls on incoming mail880642
Node: Host checking using RBL883407
Node: Other host checking887832
Node: Sender checking889504
Node: Control of relaying890192
Node: Customizing prohibition messages898285
Node: System-wide message filtering901848
Node: The system message filter902609
Node: Additional commands for system filters905503
Node: Per-address filtering909336
Node: SMTP processing910446
Node: Outgoing SMTP over TCP/IP911558
Node: Errors in outgoing SMTP915731
Node: Variable Envelope Return Paths (VERP)922513
Node: Incoming SMTP messages over TCP/IP924761
Node: The VRFY and EXPN and DEBUG commands929468
Node: The ETRN command930583
Node: Incoming local SMTP933608
Node: Outgoing batched SMTP934234
Node: Incoming batched SMTP937286
Node: Message processing939154
Node: Unqualified addresses940582
Node: The UUCP From line941640
Node: The Bcc header943661
Node: The Date header944668
Node: The Delivery-date header944911
Node: The Envelope-to header945481
Node: The From header946039
Node: The Message-id header946992
Node: The Received header947538
Node: The Return-path header947948
Node: The Sender header948484
Node: The To header949208
Node: Adding and removing headers949931
Node: Constructed addresses950854
Node: Case of local parts952214
Node: Dots in local parts953281
Node: Rewriting addresses953716
Node: Automatic mail processing955078
Node: System-wide automatic processing955547
Node: Taking copies of mail958223
Node: Automatic processing by users958973
Node: Simplified vacation processing961628
Node: Log files962926
Node: Logging to local files966982
Node: Logging to syslog968420
Node: Logging message reception971895
Node: Logging deliveries975183
Node: Deferred deliveries978077
Node: Delivery failures978945
Node: Fake deliveries979367
Node: Completion979696
Node: Other log entries980007
Node: Log level980998
Node: Message log982432
Node: Day-to-day management983548
Node: The panic log983973
Node: The reject log984479
Node: Log cycling984940
Node: Statistics985382
Node: What is Exim doing?985657
Node: Changing the configuration986869
Node: Watching the queue988277
Node: Holding domains989249
Node: Exim utilities989643
Node: Querying Exim processes990235
Node: Summarising the queue992232
Node: Extracting log information993189
Node: Cycling log files994229
Node: Making DBM files996024
Node: Individual retry times998453
Node: Database maintenance999932
Node: Mail statistics1005951
Node: -nt1009048
Node: -h<n>1009220
Node: -q01009656
Node: -q<n1>1009828
Node: -nr1010383
Node: -nr/pattern/1010563
Node: -t<n>1011331
Node: -tnl1011629
Node: -ne1011787
Node: Mailbox maintenance1011919
Node: -fcntl (exim_lock)1012890
Node: -interval (exim_lock)1013121
Node: -lockfile (exim_lock)1013441
Node: -mbx (exim_lock)1013682
Node: -retries (exim_lock)1013899
Node: -timeout (exim_lock)1014189
Node: -v (exim_lock)1014564
Node: -q (exim_lock)1014759
Node: Mailbox maintenance (continued)1014930
Node: The Exim monitor1016571
Node: Running the monitor1017190
Node: The stripcharts1019528
Node: Main action buttons1021193
Node: The log display1022707
Node: The queue display1025807
Node: The queue menu1028792
Node: Security considerations1034199
Node: Root privilege1035596
Node: Running Exim without privilege1040646
Node: Alternate configurations and macros1045081
Node: Reading forward files1045783
Node: Delivering to local files1048101
Node: IPv4 source routing1048423
Node: The VRFY and EXPN and ETRN commands in SMTP1049034
Node: Privileged users1049517
Node: Spool files1051737
Node: Use of argv[0]1052289
Node: Use of %f formatting1052750
Node: Embedded Exim path1053167
Node: Use of sprintf()1053761
Node: Use of debug_printf() and log_write()1054472
Node: Use of strcat() and strcpy()1054921
Node: Format of spool files1055214
Node: Adding new drivers or lookup types1065154
Node: Concept Index1067089

End Tag Table
