canonical - format of Postfix canonical table
The optional canonical file 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 file serves as input to the postmap(1) com-
mand. 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 canonical table.
When the table is provided via other means such as NIS,
LDAP or SQL, the same lookups are done as for ordinary
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 virtualdomain 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.
The format of the canonical table is as follows:
blanks and comments
Blank lines are ignored, as are lines beginning
When pattern matches a mail address, replace it by
the corresponding result.
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@domainaddressuser@domain is replaced by address. This form has
the highest precedence.
This form 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.
useraddressuser@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
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.
When table lookup fails, and the address localpart con-
tains the optional recipient delimiter (e.g.,
user+foo@domain), the search is repeated for the unex-
tended address (e.g. user@domain), and the unmatched
extension is propagated to the result of table lookup. The
matching order is: user+foo@domain, user@domain, user+foo,
user, and @domain.
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
Patterns are applied in the order as specified in the
table, until a pattern is found that matches the search
Results are the same as with normal indexed file lookups,
with the additional feature that parenthesized substrings
from the pattern can be interpolated as $1, $2 and so on.
The table format does not understand quoting conventions.
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 postfixreload
command after a configuration change.
List of canonical mapping tables.
Address mapping lookup table for envelope and
header recipient addresses.
Address mapping lookup table for envelope and
header sender addresses.
Other parameters of interest:
The network interface addresses that this system
receives mail on.
List of domains that hide their subdomain struc-
List of user names that are not subject to address
List of domains that this mail system considers
The domain that is appended to locally-posted mail.
Give special treatment to owner-xxx and xxx-request
SEEALSOcleanup(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
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