TRANSPORT(5)		      File Formats Manual		  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)