    TRANSPORT(5)                                         TRANSPORT(5)

    NAME
           transport - format of Postfix transport table

    SYNOPSIS
           postmap /etc/postfix/transport

           postmap -q "string" /etc/postfix/transport

           postmap -q - /etc/postfix/transport <inputfile

    DESCRIPTION
           The  optional  transport  table  specifies  a mapping from
           email addresses  to  message  delivery  transports  and/or
           relay hosts. The mapping is used by the trivial-rewrite(8)
           daemon.

           This mapping overrides the default routing that  is  built
           into Postfix:

           mydestination
                  A  list of domains that is by default delivered via
                  $local_transport.

           virtual_mailbox_domains
                  A list of domains that is by default delivered  via
                  $virtual_transport.

           relay_domains
                  A  list of domains that is by default delivered via
                  $relay_transport.

           any other destination
                  Mail for any other destination is by default deliv-
                  ered via $default_transport.

           Normally,  the transport table is specified as a text file
           that serves as  input  to  the  postmap(1)  command.   The
           result,  an  indexed file in dbm or db format, is used for
           fast searching by the mail  system.  Execute  the  command
           postmap  /etc/postfix/transport  in  order  to rebuild the
           indexed file after changing the transport table.

           When the table is provided via other means  such  as  NIS,
           LDAP  or  SQL,  the  same lookups are done as for ordinary
           indexed files.

           Alternatively, the table can be  provided  as  a  regular-
           expression map where patterns are given as regular expres-
           sions. In that case, the lookups are done  in  a  slightly
           different  way as described in section "REGULAR EXPRESSION
           TABLES".

    TABLE FORMAT
           The format of the transport table is as follows:

           pattern result
                  When  pattern  matches  the  recipient  address  or
                  domain, use the corresponding result.

           blank lines and comments
                  Empty  lines and whitespace-only lines are ignored,
                  as are lines whose first  non-whitespace  character
                  is a `#'.

           multi-line text
                  A  logical  line starts with non-whitespace text. A
                  line that starts with whitespace continues a  logi-
                  cal line.

           The  pattern specifies an email address, a domain name, or
           a domain name hierarchy, as described  in  section  "TABLE
           LOOKUP".

           The  result  is of the form transport:nexthop.  The trans-
           port field specifies a mail  delivery  transport  such  as
           smtp  or  local. The nexthop field specifies where and how
           to deliver mail. More details are given in section "RESULT
           FORMAT".

    TABLE LOOKUP
           With lookups from indexed files such as DB or DBM, or from
           networked tables such as NIS, LDAP or  SQL,  patterns  are
           tried in the order as listed below:

           user+extension@domain transport:nexthop
                  Mail for user+extension@domain is delivered through
                  transport to nexthop.

           user@domain transport:nexthop
                  Mail for user@domain is delivered through transport
                  to nexthop.

           domain transport:nexthop
                  Mail  for  domain is delivered through transport to
                  nexthop.

           .domain transport:nexthop
                  Mail for  any  subdomain  of  domain  is  delivered
                  through  transport  to  nexthop.  This applies only
                  when the string transport_maps is not listed in the
                  parent_domain_matches_subdomains configuration set-
                  ting.  Otherwise, a domain name matches itself  and
                  its subdomains.

           Note 1: the special pattern * represents any address (i.e.
           it functions as the wild-card pattern).

           Note 2:  the  null  recipient  address  is  looked  up  as
           $empty_address_recipient@$myhostname (default: mailer-dae-
           mon@hostname).

    RESULT FORMAT
           The transport field specifies the name of a mail  delivery
           transport (the first name of a mail delivery service entry
           in the Postfix master.cf file).

           The interpretation  of  the  nexthop  field  is  transport
           dependent. In the case of SMTP, specify host:service for a
           non-default server port, and use [host] or [host]:port  in
           order  to  disable MX (mail exchanger) DNS lookups. The []
           form is required when you specify an IP address instead of
           a hostname.

           A  null  transport  and  null nexthop result means "do not
           change": use the delivery transport and  nexthop  informa-
           tion  that  would  be used when the entire transport table
           did not exist.

           A non-null transport  field  with  a  null  nexthop  field
           resets the nexthop information to the recipient domain.

           A  null  transport  field with non-null nexthop field does
           not modify the transport information.

    EXAMPLES
           In order to deliver internal mail directly, while using  a
           mail  relay  for  all other mail, specify a null entry for
           internal destinations (do not change the  delivery  trans-
           port  or  the  nexthop information) and specify a wildcard
           for all other destinations.

                my.domain    :
                .my.domain   :
                *            smtp:outbound-relay.my.domain

           In order to send mail for foo.org and its  subdomains  via
           the uucp transport to the UUCP host named foo:

                foo.org      uucp:foo
                .foo.org     uucp:foo

           When  no  nexthop  host name is specified, the destination
           domain name is used instead. For  example,  the  following
           directs  mail for user@foo.org via the slow transport to a
           mail exchanger for foo.org.  The slow transport  could  be
           something  that  runs  at  most  one delivery process at a
           time:

                foo.org      slow:

           When no transport is specified, Postfix uses the transport
           that matches the address domain class (see TRANSPORT FIELD
           discussion above).   The  following  sends  all  mail  for
           foo.org and its subdomains to host gateway.foo.org:

                foo.org      :[gateway.foo.org]
                .foo.org     :[gateway.foo.org]

           In  the  above  example,  the  []  are used to suppress MX
           lookups.  The result would  likely  point  to  your  local
           machine.

           In  the  case  of delivery via SMTP, one may specify host-
           name:service instead of just a host:

                foo.org      smtp:bar.org:2025

           This directs mail for user@foo.org to  host  bar.org  port
           2025.  Instead  of a numerical port a symbolic name may be
           used. Specify [] around the hostname in order  to  disable
           MX lookups.

           The error mailer can be used to bounce mail:

                .foo.org       error:mail for *.foo.org is not deliv-
           erable

           This causes  all  mail  for  user@anything.foo.org  to  be
           bounced.

    REGULAR EXPRESSION TABLES
           This  section  describes how the table lookups change when
           the table is given in the form of regular expressions. For
           a  description  of regular expression lookup table syntax,
           see regexp_table(5) or pcre_table(5).

           Each pattern is a regular expression that  is  applied  to
           the entire domain being looked up. Thus, some.domain.hier-
           archy is not broken up into parent domains.

           Patterns are applied in the  order  as  specified  in  the
           table,  until  a  pattern is found that matches the search
           string.

           Results are the same as with indexed  file  lookups,  with
           the  additional feature that parenthesized substrings from
           the pattern can be interpolated as $1, $2 and so on.

    CONFIGURATION PARAMETERS
           The following main.cf parameters are  especially  relevant
           to  this  topic.  See  the Postfix main.cf file for syntax
           details and for default values.  Use  the  postfix  reload
           command after a configuration change.

           empty_address_recipient
                  The  address  that is looked up instead of the null
                  sender address.

           parent_domain_matches_subdomains
                  List of Postfix features that use  domain.tld  pat-
                  terns   to  match  sub.domain.tld  (as  opposed  to
                  requiring .domain.tld patterns).

           transport_maps
                  List of transport lookup tables.

    SEE ALSO
           postmap(1) create mapping table
           trivial-rewrite(8) rewrite and resolve addresses
           pcre_table(5) format of PCRE tables
           regexp_table(5) format of POSIX regular expression tables

    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

                                                         TRANSPORT(5)