    PIPE(8)                                                                PIPE(8)

    NAME
           pipe - Postfix delivery to external command

    SYNOPSIS
           pipe [generic Postfix daemon options] command_attributes...

    DESCRIPTION
           The  pipe(8)  daemon  processes  requests from the Postfix
           queue manager to deliver messages  to  external  commands.
           This  program expects to be run from the master(8) process
           manager.

           Message  attributes  such  as  sender  address,  recipient
           address  and  next-hop  host name can be specified as com-
           mand-line macros that are  expanded  before  the  external
           command is executed.

           The  pipe(8)  daemon updates queue files and marks recipi-
           ents as finished, or it informs  the  queue  manager  that
           delivery  should  be tried again at a later time. Delivery
           status reports are sent  to  the  bounce(8),  defer(8)  or
           trace(8) daemon as appropriate.

    SINGLE-RECIPIENT DELIVERY
           Some external commands cannot handle more than one recipi-
           ent per delivery request. Examples of such transports  are
           pagers, fax machines, and so on.

           To  prevent  Postfix  from sending multiple recipients per
           delivery request, specify

               transport_destination_recipient_limit = 1

           in the Postfix main.cf file, where transport is  the  name
           in the first column of the Postfix master.cf entry for the
           pipe-based delivery transport.

    COMMAND ATTRIBUTE SYNTAX
           The external command attributes are given in the master.cf
           file at the end of a service definition.  The syntax is as
           follows:

           directory=pathname (optional, default: $queue_directory)
                  Change to the named directory before executing  the
                  external  command.  Delivery is deferred in case of
                  failure.

                  This feature is available as of Postfix 2.2.

           eol=string (optional, default: \n)
                  The output record delimiter.  Typically  one  would
                  use  either \r\n or \n. The usual C-style backslash
                  escape sequences are recognized: \a \b \f \n \r  \t
                  \v \ddd (up to three octal digits) and \\.

           flags=BDFORhqu.> (optional)
                  Optional  message  processing  flags. By default, a
                  message is copied unchanged.

                  B      Append a blank line at the end of each  mes-
                         sage.  This  is  required  by some mail user
                         agents that recognize  "From  "  lines  only
                         when preceded by a blank line.

                  D      Prepend  a "Delivered-To: recipient" message
                         header with the envelope recipient  address.
                         Note: for this to work, the transport_desti-
                         nation_recipient_limit must be 1.

                         This feature is available as of Postfix 2.0.

                  F      Prepend  a "From sender time_stamp" envelope
                         header to  the  message  content.   This  is
                         expected by, for example, UUCP software.

                  O      Prepend  an  "X-Original-To: recipient" mes-
                         sage header with the  recipient  address  as
                         given  to  Postfix.  Note: for this to work,
                         the    transport_destination_recipient_limit
                         must be 1.

                         This feature is available as of Postfix 2.0.

                  R      Prepend a Return-Path: message  header  with
                         the envelope sender address.

                  h      Fold the command-line $recipient domain name
                         and $nexthop host name to lower case.   This
                         is recommended for delivery via UUCP.

                  q      Quote  white space and other special charac-
                         ters in the command-line $sender and $recip-
                         ient address localparts (text to the left of
                         the right-most @ character), according to an
                         8-bit  transparent version of RFC 822.  This
                         is recommended  for  delivery  via  UUCP  or
                         BSMTP.

                         The  result  is  compatible with the address
                         parsing of command-line  recipients  by  the
                         Postfix sendmail(1) mail submission command.

                         The q flag affects  only  entire  addresses,
                         not the partial address information from the
                         $user, $extension or  $mailbox  command-line
                         macros.

                  u      Fold  the  command-line  $recipient  address
                         localpart (text to the left  of  the  right-
                         most  @  character)  to lower case.  This is
                         recommended for delivery via UUCP.

                  .      Prepend "." to lines starting with ".". This
                         is needed by, for example, BSMTP software.

                  >      Prepend  ">" to lines starting with "From ".
                         This is expected by, for example, UUCP soft-
                         ware.

           null_sender=replacement (default: MAILER-DAEMON)
                  Replace the null sender address, which is typically
                  used for delivery status  notifications,  with  the
                  specified  text when expanding the $sender command-
                  line macro, and when generating a From_ or  Return-
                  Path: message header.

                  If  the null sender replacement text is a non-empty
                  string then it  is  affected  by  the  q  flag  for
                  address quoting in command-line arguments.

                  The null sender replacement text may be empty; this
                  form is recommended for content filters  that  feed
                  mail back into Postfix. The empty sender address is
                  not affected by the q flag for address  quoting  in
                  command-line arguments.

                  Caution: a null sender address is easily mis-parsed
                  by naive software. For example,  when  the  pipe(8)
                  daemon executes a command such as:

                      command -f$sender -- $recipient

                  the command will mis-parse the -f option value when
                  the sender address is a null string.   For  correct
                  parsing,  specify $sender as an argument by itself.

                  This feature is  available  with  Postfix  2.3  and
                  later.

           size=size_limit (optional)
                  Messages greater in size than this limit (in bytes)
                  will be returned to the sender as undeliverable.

           user=username (required)

           user=username:groupname
                  The external command is executed with the rights of
                  the  specified  username.   The software refuses to
                  execute commands with root privileges, or with  the
                  privileges  of  the mail system owner. If groupname
                  is specified, the corresponding group  ID  is  used
                  instead of the group ID of username.

           argv=command... (required)
                  The  command to be executed. This must be specified
                  as the last command attribute.  The command is exe-
                  cuted  directly,  i.e.  without  interpretation  of
                  shell meta characters by  a  shell  command  inter-
                  preter.

                  In  the  command  argument  vector,  the  following
                  macros are recognized and replaced with correspond-
                  ing  information  from  the  Postfix  queue manager
                  delivery request.

                  In addition to the form ${name},  the  forms  $name
                  and  $(name) are also recognized.  Specify $$ where
                  a single $ is wanted.

                  ${client_address}
                         This macro expands to the remote client net-
                         work address.

                         This  is available in Postfix 2.2 and later.

                  ${client_helo}
                         This macro expands to the remote client HELO
                         command parameter.

                         This  is available in Postfix 2.2 and later.

                  ${client_hostname}
                         This macro  expands  to  the  remote  client
                         hostname.

                         This  is available in Postfix 2.2 and later.

                  ${client_protocol}
                         This macro expands to the remote client pro-
                         tocol.

                         This  is available in Postfix 2.2 and later.

                  ${extension}
                         This macro expands to the extension part  of
                         a  recipient  address.  For example, with an
                         address  user+foo@domain  the  extension  is
                         foo.

                         A   command-line   argument   that  contains
                         ${extension} expands into as  many  command-
                         line arguments as there are recipients.

                         This  information  is modified by the u flag
                         for case folding.

                  ${mailbox}
                         This macro expands  to  the  complete  local
                         part  of  a recipient address.  For example,
                         with an address user+foo@domain the  mailbox
                         is user+foo.

                         A   command-line   argument   that  contains
                         ${mailbox} expands to as  many  command-line
                         arguments as there are recipients.

                         This  information  is modified by the u flag
                         for case folding.

                  ${nexthop}
                         This macro expands to the next-hop hostname.

                         This  information  is modified by the h flag
                         for case folding.

                  ${recipient}
                         This macro expands to the complete recipient
                         address.

                         A   command-line   argument   that  contains
                         ${recipient} expands to as many command-line
                         arguments as there are recipients.

                         This  information  is  modified  by  the hqu
                         flags for quoting and case folding.

                  ${sasl_method}
                         This macro expands to the  SASL  authentica-
                         tion  mechanism used during the reception of
                         the message. An empty string  is  passed  if
                         the  message  has been received without SASL
                         authentication.

                         This is available in Postfix 2.2 and  later.

                  ${sasl_sender}
                         This  macro  expands to the SASL sender name
                         (i.e. the  original  submitter  as  per  RFC
                         2554)  used during the reception of the mes-
                         sage.

                         This is available in Postfix 2.2 and  later.

                  ${sasl_username}
                         This  macro  expands  to  the SASL user name
                         used during the reception of the message. An
                         empty  string  is  passed if the message has
                         been received without SASL authentication.

                         This is available in Postfix 2.2 and  later.

                  ${sender}
                         This  macro  expands  to the envelope sender
                         address. By default, the null sender address
                         expands   to   MAILER-DAEMON;  this  can  be
                         changed with the null_sender  attribute,  as
                         described above.

                         This  information  is modified by the q flag
                         for quoting.

                  ${size}
                         This macro expands to Postfix's idea of  the
                         message  size,  which is an approximation of
                         the size of the message as delivered.

                  ${user}
                         This macro expands to the username part of a
                         recipient  address.   For  example,  with an
                         address user+foo@domain the username part is
                         user.

                         A   command-line   argument   that  contains
                         ${user} expands into  as  many  command-line
                         arguments as there are recipients.

                         This  information  is modified by the u flag
                         for case folding.

    STANDARDS
           RFC 3463 (Enhanced status codes)

    DIAGNOSTICS
           Command exit status codes are expected to follow the  con-
           ventions  defined  in  <sysexits.h>.   Exit status 0 means
           normal successful completion.

           Postfix version  2.3  and  later  support  RFC  3463-style
           enhanced  status  codes.   If  a command terminates with a
           non-zero exit status, and the command output  begins  with
           an enhanced status code, this status code takes precedence
           over the non-zero exit status.

           Problems and transactions are logged to syslogd(8).   Cor-
           rupted  message files are marked so that the queue manager
           can move them to the corrupt queue for further inspection.

    SECURITY
           This  program  needs  a  dual personality 1) to access the
           private Postfix queue and IPC mechanisms, and 2)  to  exe-
           cute external commands as the specified user. It is there-
           fore security sensitive.

    CONFIGURATION PARAMETERS
           Changes to main.cf are picked up automatically as  pipe(8)
           processes  run  for only a limited amount of time. Use the
           command "postfix reload" to speed up a change.

           The text below provides  only  a  parameter  summary.  See
           postconf(5) for more details including examples.

    RESOURCE AND RATE CONTROLS
           In  the text below, transport is the first field in a mas-
           ter.cf entry.

           transport_destination_concurrency_limit ($default_destina-
           tion_concurrency_limit)
                  Limit the number of parallel deliveries to the same
                  destination,  for delivery via the named transport.
                  The limit is enforced by the Postfix queue manager.

           transport_destination_recipient_limit   ($default_destina-
           tion_recipient_limit)
                  Limit  the  number of recipients per message deliv-
                  ery, for delivery via  the  named  transport.   The
                  limit is enforced by the Postfix queue manager.

           transport_time_limit ($command_time_limit)
                  Limit  the  time  for delivery to external command,
                  for delivery via the named transport.  The limit is
                  enforced by the pipe delivery agent.

    MISCELLANEOUS CONTROLS
           config_directory (see 'postconf -d' output)
                  The  default  location  of  the Postfix main.cf and
                  master.cf configuration files.

           daemon_timeout (18000s)
                  How much time a Postfix daemon process may take  to
                  handle  a  request  before  it  is  terminated by a
                  built-in watchdog timer.

           export_environment (see 'postconf -d' output)
                  The list of environment variables  that  a  Postfix
                  process will export to non-Postfix processes.

           ipc_timeout (3600s)
                  The time limit for sending or receiving information
                  over an internal communication channel.

           mail_owner (postfix)
                  The UNIX system account that owns the Postfix queue
                  and most Postfix daemon processes.

           max_idle (100s)
                  The  maximum  amount  of  time that an idle Postfix
                  daemon process waits for the next  service  request
                  before exiting.

           max_use (100)
                  The  maximal number of connection requests before a
                  Postfix daemon process terminates.

           process_id (read-only)
                  The process ID  of  a  Postfix  command  or  daemon
                  process.

           process_name (read-only)
                  The  process  name  of  a Postfix command or daemon
                  process.

           queue_directory (see 'postconf -d' output)
                  The location of the Postfix top-level queue  direc-
                  tory.

           recipient_delimiter (empty)
                  The separator between user names and address exten-
                  sions (user+foo).

           syslog_facility (mail)
                  The syslog facility of Postfix logging.

           syslog_name (postfix)
                  The mail system  name  that  is  prepended  to  the
                  process  name  in  syslog  records, so that "smtpd"
                  becomes, for example, "postfix/smtpd".

    SEE ALSO
           qmgr(8), queue manager
           bounce(8), delivery status reports
           postconf(5), configuration parameters
           master(5), generic daemon options
           master(8), process manager
           syslogd(8), system logging

    LICENSE
           The Secure Mailer license must be  distributed  with  this
           software.

    AUTHOR(S)
           Wietse Venema
           IBM T.J. Watson Research
           P.O. Box 704
           Yorktown Heights, NY 10598, USA

                                                                           PIPE(8)