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 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 recip-
	      ient 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 desti-
	      nation 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, 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 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 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:ser-
       vice,  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 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@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.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 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  regu-
       lar 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)