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TRANSPORT(5) TRANSPORT(5)
<b>NAME</b>
transport - Postfix transport table format
<b>SYNOPSIS</b>
<b>postmap /etc/postfix/transport</b>
<b>postmap -q "</b><i>string</i><b>" /etc/postfix/transport</b>
<b>postmap -q - /etc/postfix/transport</b> <<i>inputfile</i>
<b>DESCRIPTION</b>
The optional <a href="transport.5.html"><b>transport</b>(5)</a> table specifies a mapping from email
addresses to message delivery transports and next-hop destinations.
Message delivery transports such as <b>local</b> or <b>smtp</b> are defined in the
<a href="master.5.html"><b>master.cf</b></a> file, and next-hop destinations are typically hosts or domain
names. The table is searched by the <a href="trivial-rewrite.8.html"><b>trivial-rewrite</b>(8)</a> daemon.
This mapping overrides the default <i>transport</i>:<i>nexthop</i> selection that is
built into Postfix:
<b><a href="postconf.5.html#local_transport">local_transport</a> (default: <a href="local.8.html">local</a>:$<a href="postconf.5.html#myhostname">myhostname</a>)</b>
This is the default for final delivery to domains listed with
<b><a href="postconf.5.html#mydestination">mydestination</a></b>, and for [<i>ipaddress</i>] destinations that match
<b>$<a href="postconf.5.html#inet_interfaces">inet_interfaces</a></b> or <b>$<a href="postconf.5.html#proxy_interfaces">proxy_interfaces</a></b>. The default <i>nexthop</i> des-
tination is the MTA hostname.
<b><a href="postconf.5.html#virtual_transport">virtual_transport</a> (default: <a href="virtual.8.html">virtual</a>:)</b>
This is the default for final delivery to domains listed with
<b><a href="postconf.5.html#virtual_mailbox_domains">virtual_mailbox_domains</a></b>. The default <i>nexthop</i> destination is the
recipient domain.
<b><a href="postconf.5.html#relay_transport">relay_transport</a> (default: relay:)</b>
This is the default for remote delivery to domains listed with
<b><a href="postconf.5.html#relay_domains">relay_domains</a></b>. In order of decreasing precedence, the <i>nexthop</i>
destination is taken from <b><a href="postconf.5.html#relay_transport">relay_transport</a></b>, <b><a href="postconf.5.html#sender_dependent_relayhost_maps">sender_depen</a>-</b>
<b><a href="postconf.5.html#sender_dependent_relayhost_maps">dent_relayhost_maps</a></b>, <b><a href="postconf.5.html#relayhost">relayhost</a></b>, or from the recipient domain.
<b><a href="postconf.5.html#default_transport">default_transport</a> (default: <a href="smtp.8.html">smtp</a>:)</b>
This is the default for remote delivery to other destinations.
In order of decreasing precedence, the <i>nexthop</i> destination is
taken from <b><a href="postconf.5.html#sender_dependent_default_transport_maps">sender_dependent_default_transport_maps</a>,</b>
<b><a href="postconf.5.html#default_transport">default_transport</a></b>, <b><a href="postconf.5.html#sender_dependent_relayhost_maps">sender_dependent_relayhost_maps</a></b>, <b><a href="postconf.5.html#relayhost">relayhost</a></b>,
or from the recipient domain.
Normally, the <a href="transport.5.html"><b>transport</b>(5)</a> table is specified as a text file that
serves as input to the <a href="postmap.1.html"><b>postmap</b>(1)</a> command. The result, an indexed file
in <b>dbm</b> or <b>db</b> format, is used for fast searching by the mail system.
Execute the command "<b>postmap /etc/postfix/transport</b>" 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 a 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".
<b>CASE FOLDING</b>
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 <a href="regexp_table.5.html">regexp</a>: or <a href="pcre_table.5.html">pcre</a>: whose lookup fields can match both upper and
lower case.
<b>TABLE FORMAT</b>
The input format for the <a href="postmap.1.html"><b>postmap</b>(1)</a> command is as follows:
<i>pattern result</i>
When <i>pattern</i> matches the recipient address or domain, use the
corresponding <i>result</i>.
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 <i>pattern</i> specifies an email address, a domain name, or a domain name
hierarchy, as described in section "TABLE SEARCH ORDER".
The <i>result</i> is of the form <i>transport:nexthop</i> and specifies how or where
to deliver mail. This is described in section "RESULT FORMAT".
<b>TABLE SEARCH ORDER</b>
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:
<i>user+extension@domain transport</i>:<i>nexthop</i>
Deliver mail for <i>user+extension@domain</i> through <i>transport</i> to <i>nex-</i>
<i>thop</i>.
<i>user@domain transport</i>:<i>nexthop</i>
Deliver mail for <i>user@domain</i> through <i>transport</i> to <i>nexthop</i>.
<i>domain transport</i>:<i>nexthop</i>
Deliver mail for <i>domain</i> through <i>transport</i> to <i>nexthop</i>.
<i>.domain transport</i>:<i>nexthop</i>
Deliver mail for any subdomain of <i>domain</i> through <i>transport</i> to
<i>nexthop</i>. This applies only when the string <b><a href="postconf.5.html#transport_maps">transport_maps</a></b> is not
listed in the <b><a href="postconf.5.html#parent_domain_matches_subdomains">parent_domain_matches_subdomains</a></b> configuration
setting. Otherwise, a domain name matches itself and its subdo-
mains.
<b>*</b> <i>transport</i>:<i>nexthop</i>
The special pattern <b>*</b> 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
<b>$<a href="postconf.5.html#empty_address_recipient">empty_address_recipient</a></b>@<b>$<a href="postconf.5.html#myhostname">myhostname</a></b> (default: mailer-daemon@hostname).
Note 2: <i>user@domain</i> or <i>user+extension@domain</i> lookup is available in
Postfix 2.0 and later.
<b>RESULT FORMAT</b>
The lookup result is of the form <i>transport</i><b>:</b><i>nexthop</i>. The <i>transport</i>
field specifies a mail delivery transport such as <b>smtp</b> or <b>local</b>. The
<i>nexthop</i> 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 <a href="master.5.html"><b>mas-</b>
<b>ter.cf</b></a> file).
The nexthop field usually specifies one recipient domain or hostname.
In the case of the Postfix SMTP/LMTP client, the nexthop field may con-
tain 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 <i>host</i>:<i>service</i>, and disable MX
(mail exchanger) DNS lookups with [<i>host</i>] or [<i>host</i>]:<i>port</i>. The [] form is
required when you specify an IP address instead of a hostname.
A null <i>transport</i> and null <i>nexthop</i> field 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 <i>transport</i> field with a null <i>nexthop</i> field resets the nexthop
information to the recipient domain.
A null <i>transport</i> field with non-null <i>nexthop</i> field does not modify the
transport information.
<b>EXAMPLES</b>
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.
<b>my.domain :</b>
<b>.my.domain :</b>
<b>* <a href="smtp.8.html">smtp</a>:outbound-relay.my.domain</b>
In order to send mail for <b>example.com</b> and its subdomains via the <b>uucp</b>
transport to the UUCP host named <b>example</b>:
<b>example.com uucp:example</b>
<b>.example.com uucp:example</b>
When no nexthop host name is specified, the destination domain name is
used instead. For example, the following directs mail for <i>user</i>@<b>exam-</b>
<b>ple.com</b> via the <b>slow</b> transport to a mail exchanger for <b>example.com</b>.
The <b>slow</b> transport could be configured to run at most one delivery
process at a time:
<b>example.com slow:</b>
When no transport is specified, Postfix uses the transport that matches
the address domain class (see DESCRIPTION above). The following sends
all mail for <b>example.com</b> and its subdomains to host <b>gateway.exam-</b>
<b>ple.com</b>:
<b>example.com :[gateway.example.com]</b>
<b>.example.com :[gateway.example.com]</b>
In the above example, the [] suppress MX lookups. This prevents mail
routing loops when your machine is primary MX host for <b>example.com</b>.
In the case of delivery via SMTP or LMTP, one may specify <i>host</i>:<i>service</i>
instead of just a host:
<b>example.com <a href="smtp.8.html">smtp</a>:bar.example:2025</b>
This directs mail for <i>user</i>@<b>example.com</b> to host <b>bar.example</b> port <b>2025</b>.
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):
<b>example.com <a href="smtp.8.html">smtp</a>:bar.example, foo.example</b>
This tries to deliver to <b>bar.example</b> before trying to deliver to
<b>foo.example</b>.
The error mailer can be used to bounce mail:
<b>.example.com <a href="error.8.html">error</a>:mail for *.example.com is not deliverable</b>
This causes all mail for <i>user</i>@<i>anything</i><b>.example.com</b> to be bounced.
<b>REGULAR EXPRESSION TABLES</b>
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 <a href="regexp_table.5.html"><b>regexp_table</b>(5)</a> or <a href="pcre_table.5.html"><b>pcre_table</b>(5)</a>.
Each pattern is a regular expression that is applied to the entire
address being looked up. Thus, <i>some.domain.hierarchy</i> is not looked up
via its parent domains, nor is <i>user+foo@domain</i> looked up as
<i>user@domain</i>.
Patterns are applied in the order as specified in the table, until a
pattern is found that matches the search string.
The <a href="trivial-rewrite.8.html"><b>trivial-rewrite</b>(8)</a> 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).
<b>TCP-BASED TABLES</b>
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 <a href="tcp_table.5.html"><b>tcp_table</b>(5)</a>. This feature is not
available up to and including Postfix version 2.4.
Each lookup operation uses the entire recipient address once. Thus,
<i>some.domain.hierarchy</i> is not looked up via its parent domains, nor is
<i>user+foo@domain</i> looked up as <i>user@domain</i>.
Results are the same as with indexed file lookups.
<b>CONFIGURATION PARAMETERS</b>
The following <a href="postconf.5.html"><b>main.cf</b></a> parameters are especially relevant. The text
below provides only a parameter summary. See <a href="postconf.5.html"><b>postconf</b>(5)</a> for more
details including examples.
<b><a href="postconf.5.html#empty_address_recipient">empty_address_recipient</a> (MAILER-DAEMON)</b>
The recipient of mail addressed to the null address.
<b><a href="postconf.5.html#parent_domain_matches_subdomains">parent_domain_matches_subdomains</a> (see 'postconf -d' output)</b>
A list of Postfix features where the pattern "example.com" also
matches subdomains of example.com, instead of requiring an
explicit ".example.com" pattern.
<b><a href="postconf.5.html#transport_maps">transport_maps</a> (empty)</b>
Optional lookup tables with mappings from recipient address to
(message delivery transport, next-hop destination).
<b>SEE ALSO</b>
<a href="trivial-rewrite.8.html">trivial-rewrite(8)</a>, rewrite and resolve addresses
<a href="master.5.html">master(5)</a>, <a href="master.5.html">master.cf</a> file format
<a href="postconf.5.html">postconf(5)</a>, configuration parameters
<a href="postmap.1.html">postmap(1)</a>, Postfix lookup table manager
<b>README FILES</b>
<a href="ADDRESS_REWRITING_README.html">ADDRESS_REWRITING_README</a>, address rewriting guide
<a href="DATABASE_README.html">DATABASE_README</a>, Postfix lookup table overview
<a href="FILTER_README.html">FILTER_README</a>, external content filter
<b>LICENSE</b>
The Secure Mailer license must be distributed with this software.
<b>AUTHOR(S)</b>
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
TRANSPORT(5)
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