CANONICAL(5) CANONICAL(5)
NAME
canonical - format of Postfix canonical table
SYNOPSIS
postmap /etc/postfix/canonical
postmap -q "string" /etc/postfix/canonical
postmap -q - /etc/postfix/canonical <inputfile
DESCRIPTION
The optional canonical table specifies an address mapping
for local and non-local addresses. The mapping is used by
the cleanup(8) daemon. The address mapping is recursive.
Normally, the canonical 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/canonical in order to rebuild the
indexed file after changing the text file.
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 expres-
sions. In that case, the lookups are done in a slightly
different way as described below.
The canonical mapping affects both message header
addresses (i.e. addresses that appear inside messages) and
message envelope addresses (for example, the addresses
that are used in SMTP protocol commands). Think Sendmail
rule set S3, if you like.
Typically, one would use the canonical table to replace
login names by Firstname.Lastname, or to clean up
addresses produced by legacy mail systems.
The canonical mapping is not to be confused with virtual
domain support. Use the virtual(5) map for that purpose.
The canonical mapping is not to be confused with local
aliasing. Use the aliases(5) map for that purpose.
TABLE FORMAT
The format of the canonical table is as follows:
pattern result
When pattern matches a mail address, replace it by
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 logi-
cal line.
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@domain address
user@domain is replaced by address. This form has
the highest precedence.
This is useful to clean up addresses produced by
legacy mail systems. It can also be used to pro-
duce Firstname.Lastname style addresses, but see
below for a simpler solution.
user address
user@site is replaced by address when site is equal
to $myorigin, when site is listed in $mydestina-
tion, or when it is listed in $inet_interfaces.
This form is useful for replacing login names by
Firstname.Lastname.
@domain address
Every address in domain is replaced by address.
This form has the lowest precedence.
In all the above forms, when address has the form @other-
domain, the result is the same user in otherdomain.
ADDRESS EXTENSION
When a mail address localpart contains the optional recip-
ient delimiter (e.g., user+foo@domain), the lookup order
becomes: user+foo@domain, user@domain, user+foo, user, and
@domain. An unmatched address extension (+foo) is propa-
gated to the result of table lookup.
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, user@domain mail
addresses are not broken up into their user and @domain
constituent parts, nor is user+foo broken up into user and
foo.
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 feature that parenthesized substrings from
the pattern can be interpolated as $1, $2 and so on.
BUGS
The table format does not understand quoting conventions.
CONFIGURATION PARAMETERS
The following main.cf parameters are especially relevant
to this topic. See the Postfix main.cf file for syntax
details and for default values. Use the postfix reload
command after a configuration change.
canonical_maps
List of canonical mapping tables.
recipient_canonical_maps
Address mapping lookup table for envelope and
header recipient addresses.
sender_canonical_maps
Address mapping lookup table for envelope and
header sender addresses.
Other parameters of interest:
inet_interfaces
The network interface addresses that this system
receives mail on. You need to stop and start Post-
fix when this parameter changes.
masquerade_classes
List of address classes subject to masquerading:
zero or more of envelope_sender, envelope_recipi-
ent, header_sender, header_recipient.
masquerade_domains
List of domains that hide their subdomain struc-
ture.
masquerade_exceptions
List of user names that are not subject to address
masquerading.
mydestination
List of domains that this mail system considers
local.
myorigin
The domain that is appended to locally-posted mail.
owner_request_special
Give special treatment to owner-xxx and xxx-request
addresses.
SEE ALSO
cleanup(8) canonicalize and enqueue mail
postmap(1) create mapping table
virtual(5) virtual domain mapping
pcre_table(5) format of PCRE tables
regexp_table(5) format of POSIX regular expression tables
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
CANONICAL(5)