TRANSPORT(5)                                                      TRANSPORT(5)



NAME
       transport - Postfix transport table format

SYNOPSIS
       postmap /etc/postfix/transport

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

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

DESCRIPTION
       The   optional  transport(5)  table  specifies  a  mapping  from  email
       addresses to message delivery  transports  and  next-hop  destinations.
       Message  delivery  transports  such as local or smtp are defined in the
       master.cf file, and next-hop destinations are typically hosts or domain
       names. The table is searched by the trivial-rewrite(8) daemon.

       This  mapping overrides the default transport:nexthop selection that is
       built into Postfix:

       local_transport (default: local:$myhostname)
              This is the default for final delivery to  domains  listed  with
              mydestination,  and  for  [ipaddress]  destinations  that  match
              $inet_interfaces or $proxy_interfaces. The default nexthop  des-
              tination is the MTA hostname.

       virtual_transport (default: virtual:)
              This  is  the  default for final delivery to domains listed with
              virtual_mailbox_domains. The default nexthop destination is  the
              recipient domain.

       relay_transport (default: relay:)
              This  is  the default for remote delivery to domains listed with
              relay_domains. In order of decreasing  precedence,  the  nexthop
              destination   is   taken   from  relay_transport,  sender_depen-
              dent_relayhost_maps, relayhost, or from the recipient domain.

       default_transport (default: smtp:)
              This is the default for remote delivery to  other  destinations.
              In  order  of  decreasing precedence, the nexthop destination is
              taken       from        sender_dependent_default_transport_maps,
              default_transport,  sender_dependent_relayhost_maps,  relayhost,
              or from the recipient domain.

       Normally, the transport(5) 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"  to rebuild an
       indexed file after changing the corresponding 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  expressions,  or  lookups  can  be
       directed  to TCP-based server. In those case, the lookups are done in a
       slightly different way as described  below  under  "REGULAR  EXPRESSION
       TABLES" or "TCP-BASED TABLES".

CASE FOLDING
       The  search string is folded to lowercase before database lookup. As of
       Postfix 2.3, the search string is not case folded with  database  types
       such  as  regexp: or pcre: whose lookup fields can match both upper and
       lower case.

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 logical 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 SEARCH ORDER
       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
              Deliver mail for user+extension@domain through transport to nex-
              thop.

       user@domain transport:nexthop
              Deliver mail for user@domain through transport to nexthop.

       domain transport:nexthop
              Deliver mail for domain through transport to nexthop.

       .domain transport:nexthop
              Deliver mail for any subdomain of domain  through  transport  to
              nexthop. This applies only when the string transport_maps is not
              listed  in  the  parent_domain_matches_subdomains  configuration
              setting.  Otherwise, a domain name matches itself and its subdo-
              mains.

       * transport:nexthop
              The special pattern * represents any address (i.e. it  functions
              as  the  wild-card  pattern,  and is unique to Postfix transport
              tables).

       Note   1:   the   null   recipient   address   is    looked    up    as
       $empty_address_recipient@$myhostname (default: mailer-daemon@hostname).

       Note 2: user@domain or user+extension@domain  lookup  is  available  in
       Postfix 2.0 and later.

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  mas-
       ter.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 information 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 transport or the nexthop information) and spec-
       ify 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@exam-
       ple.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.exam-
       ple.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 hostname: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.

       The trivial-rewrite(8) server disallows regular expression substitution
       of $1 etc. in regular expression lookup tables, because that could open
       a security hole (Postfix version 2.3 and later).

TCP-BASED TABLES
       This section describes how the table lookups change  when  lookups  are
       directed   to  a  TCP-based  server.  For  a  description  of  the  TCP
       client/server lookup protocol, see tcp_table(5).  This feature  is  not
       available up to and including Postfix version 2.4.

       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 patterns  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
       master(5), master.cf file format
       postconf(5), configuration parameters
       postmap(1), Postfix lookup table manager

README FILES
       Use  "postconf readme_directory" or "postconf html_directory" to locate
       this information.
       ADDRESS_REWRITING_README, address rewriting guide
       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)

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