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  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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