    TRANSPORT(5)                                         TRANSPORT(5)

    NAME
           transport - format of Postfix transport table

    SYNOPSIS
           postmap /etc/postfix/transport

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

           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 below.

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

           blanks and comments
                  Blank lines are ignored,  as  are  lines  beginning
                  with `#'.

           leading whitespace
                  Lines  that begin with whitespace continue the pre-
                  vious line.

           pattern result
                  When pattern matches the  domain,  use  the  corre-
                  sponding result.

           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:

           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.

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    TRANSPORT(5)                                         TRANSPORT(5)

           Note:  transport  map entries take precedence over domains
           specified in the mydestination parameter. If you  use  the
           optional  transport  map,  it  may  be  safer  to  specify
           explicit entries for all domains specified  in  mydestina-
           tion, for example:

                hostname.my.domain   local:
                localhost.my.domain      local:

           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  can  also be used with IP addresses instead of host-
           names.

    EXAMPLES
           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, the default  transport  is
           used, as specified via the default_transport configuration
           parameter. 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.

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    TRANSPORT(5)                                         TRANSPORT(5)

           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 normal 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.

           transport_maps
                  List of transport lookup tables.

           Other parameters of interest:

           default_transport
                  The transport to use when no transport  is  explic-
                  itly specified.

           relayhost
                  The default host to send to when no transport table
                  entry matches.

    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.

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    TRANSPORT(5)                                         TRANSPORT(5)

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

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