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".

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:

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

       user@domain transport:nexthop
              Deliver mail for user@domain 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-
       mon@hostname).

       Note 3: 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 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  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 2.2.

       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)