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, or lookups can be directed to TCP-based server.  In
       that  case,  the  lookups are done in a slightly different
       way as described below under "REGULAR  EXPRESSION  TABLES"
       and "TCP-BASED TABLES".

TABLE FORMAT
       The input format for the postmap(1) command 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    address    being    looked    up.   Thus,
       some.domain.hierarchy is not looked up up via  its  parent
       domains,  nor is user+foo@domain looked up as user@domain.

       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.

TCP-BASED TABLES
       This section describes how the table lookups  change  when
       lookups are directed to a TCP-based server. For a descrip-
       tion  of  the  TCP  client/server  lookup  protocol,   see
       tcp_table(5).

       Each  lookup  operation  uses the entire recipient address
       once.  Thus, some.domain.hierarchy is not  looked  up  via
       its  parent  domains,  nor is user+foo@domain looked up as
       user@domain.

       Results are the same as with indexed file lookups.

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
       tcp_table(5) TCP client/server table lookup protocol

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)