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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 hosts. 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] des-
              tinations    that    match    $inet_interfaces   or
              $proxy_interfaces. The default nexthop  destination
              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_dependent_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"  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".

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 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 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:

       [email protected] transport:nexthop
              Deliver  mail  for  [email protected]   through
              transport to nexthop.

       [email protected] transport:nexthop
              Deliver  mail  for [email protected] through transport to
              nexthop.

       domain transport:nexthop
              Deliver mail for domain through transport  to  nex-
              thop.

       .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 par-
              ent_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-
       [email protected]).

       Note  3:  [email protected]  or  [email protected] 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 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 [email protected] looked up as  [email protected].

       Patterns  are applied in the order as specified in the ta-
       ble, 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_ta-
       ble(5).  This feature is not available up to and including
       Postfix version 2.3.

       Each  lookup  operation  uses the entire recipient address
       once.  Thus, some.domain.hierarchy is not  looked  up  via
       its  parent  domains,  nor is [email protected] looked up as
       [email protected].

       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)