NAME
generic - Postfix generic table format
SYNOPSIS
postmap /etc/postfix/generic
postmap -q "string" /etc/postfix/generic
postmap -q - /etc/postfix/generic <inputfile
DESCRIPTION
The optional
generic(5) table specifies an address mapping that applies
when mail is delivered. This is the opposite of
canonical(5) mapping,
which applies when mail is received.
Typically, one would use the
generic(5) table on a system that does not
have a valid Internet domain name and that uses something like
localdomain.local instead. The
generic(5) table is then used by
the
smtp(8) client to transform local mail addresses into valid
Internet mail addresses when mail has to be sent across the Internet. See the
EXAMPLE section at the end of this document.
The
generic(5) 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).
Normally, the
generic(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/generic" to
rebuild an indexed file after changing the corresponding 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 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 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 logical line.
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@domain address
- Replace user@domain by address. This
form has the highest precedence.
- user address
- Replace user@site by address when
site is equal to $ myorigin, when site is listed in $
mydestination, or when it is listed in $inet_interfaces or $
proxy_interfaces.
- @domain address
- Replace other addresses in domain by address.
This form has the lowest precedence.
RESULT ADDRESS REWRITING
The lookup result is subject to address rewriting:
- •
- When the result has the form @otherdomain, the
result becomes the same user in otherdomain.
- •
- When "append_at_myorigin=yes", append
" @$myorigin" to addresses without
"@domain".
- •
- When "append_dot_mydomain=yes", append
" .$mydomain" to addresses without
".domain".
ADDRESS EXTENSION
When a mail address localpart contains the optional recipient delimiter (e.g.,
user+foo@
domain), the lookup order becomes:
user+foo@
domain,
user@
domain,
user+foo,
user, and @
domain.
The
propagate_unmatched_extensions parameter controls whether an
unmatched address extension (
+foo) is propagated 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.
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 address once. 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.
Results are the same as with indexed file lookups.
EXAMPLE
The following shows a generic mapping with an indexed file. When mail is sent to
a remote host via SMTP, this replaces
his@localdomain.local by his ISP
mail address, replaces
her@localdomain.local by her ISP mail address,
and replaces other local addresses by his ISP account, with an address
extension of
+local (this example assumes that the ISP supports
"+" style address extensions).
/etc/postfix/main.cf:
smtp_generic_maps = hash:/etc/postfix/generic
/etc/postfix/generic:
his@localdomain.local hisaccount@hisisp.example
her@localdomain.local heraccount@herisp.example
@localdomain.local hisaccount+local@hisisp.example
Execute the command "
postmap /etc/postfix/generic" whenever
the table is changed. Instead of
hash, some systems use
dbm
database files. To find out what tables your system supports use the command
"
postconf -m".
BUGS
The table format does not understand quoting conventions.
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.
- smtp_generic_maps
- Address mapping lookup table for envelope and header sender
and recipient addresses while delivering mail via SMTP.
- propagate_unmatched_extensions
- A list of address rewriting or forwarding mechanisms that
propagate an address extension from the original address to the result.
Specify zero or more of canonical, virtual, alias,
forward, include, or generic.
Other parameters of interest:
- inet_interfaces
- The network interface addresses that this system receives
mail on. You need to stop and start Postfix when this parameter
changes.
- proxy_interfaces
- Other interfaces that this machine receives mail on by way
of a proxy agent or network address translator.
- 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
postmap(1), Postfix lookup table manager
postconf(5), configuration parameters
smtp(8), Postfix SMTP client
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
STANDARD_CONFIGURATION_README, configuration examples
LICENSE
The Secure Mailer license must be distributed with this software.
HISTORY
A genericstable feature appears in the Sendmail MTA.
This feature is available in Postfix 2.2 and later.
AUTHOR(S)
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