.\"	$NetBSD: generic.5,v 1.2.14.1 2023/12/25 12:54:40 martin Exp $
.\"
.TH GENERIC 5 
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.SH NAME
generic
\-
Postfix generic table format
.SH "SYNOPSIS"
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.nf
\fBpostmap /etc/postfix/generic\fR

\fBpostmap \-q "\fIstring\fB" /etc/postfix/generic\fR

\fBpostmap \-q \- /etc/postfix/generic <\fIinputfile\fR
.SH DESCRIPTION
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.fi
The optional \fBgeneric\fR(5) table specifies an address
mapping that applies when mail is delivered. This is the
opposite of \fBcanonical\fR(5) mapping, which applies when
mail is received.

Typically, one would use the \fBgeneric\fR(5) table on a
system that does not have a valid Internet domain name and
that uses something like \fIlocaldomain.local\fR instead.
The \fBgeneric\fR(5) table is then used by the \fBsmtp\fR(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 \fBgeneric\fR(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 \fBgeneric\fR(5) table is specified as a
text file that serves as input to the \fBpostmap\fR(1)
command.  The result, an indexed file in \fBdbm\fR or
\fBdb\fR format, is used for fast searching by the mail
system. Execute the command "\fBpostmap /etc/postfix/generic\fR"
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 a TCP\-based server. In those cases, the lookups
are done in a slightly different way as described below under
"REGULAR EXPRESSION TABLES" or "TCP\-BASED TABLES".
.SH "CASE FOLDING"
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.nf
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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.
.SH "TABLE FORMAT"
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The input format for the \fBpostmap\fR(1) command is as follows:
.IP "\fIpattern result\fR"
When \fIpattern\fR matches a mail address, replace it by the
corresponding \fIresult\fR.
.IP "blank lines and comments"
Empty lines and whitespace\-only lines are ignored, as
are lines whose first non\-whitespace character is a `#'.
.IP "multi\-line text"
A logical line starts with non\-whitespace text. A line that
starts with whitespace continues a logical line.
.SH "TABLE SEARCH ORDER"
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With lookups from indexed files such as DB or DBM, or from networked
tables such as NIS, LDAP or SQL, each \fIuser\fR@\fIdomain\fR
query produces a sequence of query patterns as described below.

Each query pattern is sent to each specified lookup table
before trying the next query pattern, until a match is
found.
.IP "\fIuser\fR@\fIdomain address\fR"
Replace \fIuser\fR@\fIdomain\fR by \fIaddress\fR. This form
has the highest precedence.
.IP "\fIuser address\fR"
Replace \fIuser\fR@\fIsite\fR by \fIaddress\fR when \fIsite\fR is
equal to $\fBmyorigin\fR, when \fIsite\fR is listed in
$\fBmydestination\fR, or when it is listed in $\fBinet_interfaces\fR
or $\fBproxy_interfaces\fR.
.IP "@\fIdomain address\fR"
Replace other addresses in \fIdomain\fR by \fIaddress\fR.
This form has the lowest precedence.
.SH "RESULT ADDRESS REWRITING"
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The lookup result is subject to address rewriting:
.IP \(bu
When the result has the form @\fIotherdomain\fR, the
result becomes the same \fIuser\fR in \fIotherdomain\fR.
.IP \(bu
When "\fBappend_at_myorigin=yes\fR", append "\fB@$myorigin\fR"
to addresses without "@domain".
.IP \(bu
When "\fBappend_dot_mydomain=yes\fR", append
"\fB.$mydomain\fR" to addresses without ".domain".
.SH "ADDRESS EXTENSION"
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When a mail address localpart contains the optional recipient delimiter
(e.g., \fIuser+foo\fR@\fIdomain\fR), the lookup order becomes:
\fIuser+foo\fR@\fIdomain\fR, \fIuser\fR@\fIdomain\fR, \fIuser+foo\fR,
\fIuser\fR, and @\fIdomain\fR.

The \fBpropagate_unmatched_extensions\fR parameter controls whether
an unmatched address extension (\fI+foo\fR) is propagated to the
result of table lookup.
.SH "REGULAR EXPRESSION TABLES"
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.nf
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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 \fBregexp_table\fR(5)
or \fBpcre_table\fR(5).

Each pattern is a regular expression that is applied to the entire
address being looked up. Thus, \fIuser@domain\fR mail addresses are not
broken up into their \fIuser\fR and \fI@domain\fR constituent parts,
nor is \fIuser+foo\fR broken up into \fIuser\fR and \fIfoo\fR.

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 \fB$1\fR, \fB$2\fR and so on.
.SH "TCP-BASED TABLES"
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.nf
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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 \fBtcp_table\fR(5).
This feature is available in Postfix 2.5 and later.

Each lookup operation uses the entire address once.  Thus,
\fIuser@domain\fR mail addresses are not broken up into their
\fIuser\fR and \fI@domain\fR constituent parts, nor is
\fIuser+foo\fR broken up into \fIuser\fR and \fIfoo\fR.

Results are the same as with indexed file lookups.
.SH "EXAMPLE"
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The following shows a generic mapping with an indexed file.
When mail is sent to a remote host via SMTP, this replaces
\fIhis@localdomain.local\fR by his ISP mail address, replaces
\fIher@localdomain.local\fR by her ISP mail address, and
replaces other local addresses by his ISP account, with
an address extension of \fI+local\fR (this example assumes
that the ISP supports "+" style address extensions).

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.nf
/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

.ad
.fi
Execute the command "\fBpostmap /etc/postfix/generic\fR"
whenever the table is changed.  Instead of \fBhash\fR, some
systems use \fBdbm\fR database files. To find out what
tables your system supports use the command "\fBpostconf
\-m\fR".
.SH BUGS
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The table format does not understand quoting conventions.
.SH "CONFIGURATION PARAMETERS"
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The following \fBmain.cf\fR parameters are especially relevant.
The text below provides only a parameter summary. See
\fBpostconf\fR(5) for more details including examples.
.IP "\fBsmtp_generic_maps (empty)\fR"
Optional lookup tables that perform address rewriting in the
Postfix SMTP client, typically to transform a locally valid address into
a globally valid address when sending mail across the Internet.
.IP "\fBpropagate_unmatched_extensions (canonical, virtual)\fR"
What address lookup tables copy an address extension from the lookup
key to the lookup result.
.PP
Other parameters of interest:
.IP "\fBinet_interfaces (all)\fR"
The network interface addresses that this mail system receives
mail on.
.IP "\fBproxy_interfaces (empty)\fR"
The network interface addresses that this mail system receives mail
on by way of a proxy or network address translation unit.
.IP "\fBmydestination ($myhostname, localhost.$mydomain, localhost)\fR"
The list of domains that are delivered via the $local_transport
mail delivery transport.
.IP "\fBmyorigin ($myhostname)\fR"
The domain name that locally\-posted mail appears to come
from, and that locally posted mail is delivered to.
.IP "\fBowner_request_special (yes)\fR"
Enable special treatment for owner\-\fIlistname\fR entries in the
\fBaliases\fR(5) file, and don't split owner\-\fIlistname\fR and
\fIlistname\fR\-request address localparts when the recipient_delimiter
is set to "\-".
.SH "SEE ALSO"
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postmap(1), Postfix lookup table manager
postconf(5), configuration parameters
smtp(8), Postfix SMTP client
.SH "README FILES"
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Use "\fBpostconf readme_directory\fR" or
"\fBpostconf html_directory\fR" to locate this information.
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ADDRESS_REWRITING_README, address rewriting guide
DATABASE_README, Postfix lookup table overview
STANDARD_CONFIGURATION_README, configuration examples
.SH "LICENSE"
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.nf
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The Secure Mailer license must be distributed with this software.
.SH HISTORY
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A genericstable feature appears in the Sendmail MTA.

This feature is available in Postfix 2.2 and later.
.SH "AUTHOR(S)"
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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