SYNOPSIS
postmap /etc/postfix/transport
postmap -q "string" /etc/postfix/transport
postmap -q - /etc/postfix/transport <inputfile
DESCRIPTION
The optional transport table specifies a mapping from email addresses
to message delivery transports and/or relay hosts. The mapping is used
by the trivial-rewrite(8) daemon.
This mapping overrides the default routing that is built into Postfix:
mydestination
A list of domains that is by default delivered via $local_trans-
port. This also includes domains that match $inet_interfaces or
$proxy_interfaces.
virtual_mailbox_domains
A list of domains that is by default delivered via $vir-
tual_transport.
relay_domains
A list of domains that is by default delivered via $relay_trans-
port.
any other destination
Mail for any other destination is by default delivered via
$default_transport.
Normally, the transport 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 expressions, 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.
TABLE LOOKUP
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
Mail for user+extension@domain is delivered through transport to
nexthop.
user@domain transport:nexthop
Mail for user@domain is delivered through transport to nexthop.
domain transport:nexthop
Mail for domain is delivered through transport to nexthop.
.domain transport:nexthop
Mail for any subdomain of domain is delivered 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.
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-daemon@hostname).
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
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.
Results are the same as with indexed file lookups, with the additional
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
postconf(5), configuration parameters
postmap(1), Postfix lookup table manager
README FILES
Use "postconf readme_directory" or "postconf html_directory" to locate
this information.
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)
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