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 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
               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,

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     TRANSPORT(5)                                         TRANSPORT(5)

          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

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     TRANSPORT(5)                                         TRANSPORT(5)

               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 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
               subdomains.

          * 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 master.cf file).

          The nexthop field usually specifies one recipient domain  or
          hostname.  In  the case of the Postfix SMTP/LMTP client, the
          nexthop field may contain a  list  of  nexthop  destinations
          separated by comma or whitespace (Postfix 3.5 and later).

          The syntax of a nexthop destination is transport  dependent.
          With  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  field  means  "do  not

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     TRANSPORT(5)                                         TRANSPORT(5)

          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 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 or LMTP,  one  may  specify
          host:service instead of just a host:

               example.com      smtp:bar.example:2025

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     TRANSPORT(5)                                         TRANSPORT(5)

          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.

          Deliveries via SMTP or LMTP  support  multiple  destinations
          (Postfix >= 3.5):

               example.com      smtp:bar.example, foo.example

          This tries  to  deliver  to  bar.example  before  trying  to
          deliver to foo.example.

          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.

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     TRANSPORT(5)                                         TRANSPORT(5)

     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 (MAILER-DAEMON)
               The recipient of mail addressed to the null address.

          parent_domain_matches_subdomains (see 'postconf -d' output)
               A  list  of  Postfix   features   where   the   pattern
               "example.com"  also  matches subdomains of example.com,
               instead  of  requiring   an   explicit   ".example.com"
               pattern.

          transport_maps (empty)
               Optional lookup tables  with  mappings  from  recipient
               address   to   (message  delivery  transport,  next-hop
               destination).

     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

          Wietse Venema
          Google, Inc.
          111 8th Avenue
          New York, NY 10011, USA

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