Postfix manual - transport(5)

    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. This also includes  domains  that
                  match $inet_interfaces or $proxy_interfaces.

           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 and  specifies
           how or where to deliver mail. This is described 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  lookup  result is of the form transport:nexthop.  The
           transport field specifies a mail delivery  transport  such
           as  smtp  or  local. The nexthop field specifies where and
           how to deliver mail.

           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 a service on a
           non-default port as host:service,  and  disable  MX  (mail
           exchanger)  DNS lookups with [host] or [host]:port. 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 example.com and  its  subdomains
           via the uucp transport to the UUCP host named example:

                example.com      uucp:example
                .example.com     uucp:example

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

                example.com      slow:

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

                example.com      :[gateway.example.com]
                .example.com     :[gateway.example.com]

           In  the  above  example, the [] suppress MX lookups.  This
           prevents mail routing loops when your machine  is  primary
           MX host for example.com.

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

                example.com      smtp:bar.example:2025

           This directs mail for user@example.com to host bar.example
           port 2025. Instead of a numerical port a symbolic name may
           be used. Specify [] around the hostname if MX lookups must
           be disabled.

           The error mailer can be used to bounce mail:

                .example.com      error:mail for *.example.com is not
           deliverable

           This causes all mail for user@anything.example.com  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  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).   This  feature  is not available in Postfix
           version 2.1.

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

           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
           trivial-rewrite(8), rewrite and resolve addresses
           postconf(5), configuration parameters
           postmap(1), Postfix lookup table manager

    README FILES
           DATABASE_README, Postfix lookup table overview
           FILTER_README, external content filter

    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)