.TH REGEXP_TABLE 5
.ad
.fi
.SH NAME
regexp_table
\-
format of Postfix regular expression tables
.SH SYNOPSIS
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.nf
\fBregexp:/etc/postfix/\fIfilename\fR
\fBpostmap -q "\fIstring\fB" regexp:/etc/postfix/\fIfilename\fR
\fBpostmap -q - regexp:/etc/postfix/\fIfilename\fR <\fIinputfile\fR
.SH DESCRIPTION
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The Postfix mail system uses optional tables for address
rewriting or mail routing. These tables are usually in
\fBdbm\fR or \fBdb\fR format. Alternatively, lookup tables
can be specified in POSIX regular expression form.
To find out what types of lookup tables your Postfix system
supports use the \fBpostconf -m\fR command.
To test lookup tables, use the \fBpostmap\fR command as
described in the SYNOPSIS above.
The general form of a Postfix regular expression table is:
.IP "\fB/\fIpattern\fB/\fIflags result\fR"
.IP "\fB!/\fIpattern\fB/\fIflags result\fR"
When \fIpattern\fR matches (does not match) a search string,
use the corresponding \fIresult\fR value.
.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.
.IP "\fBif /\fIpattern\fB/\fIflags\fR"
.IP "\fBif !/\fIpattern\fB/\fIflags\fR"
.IP "\fBendif\fR"
Examine the lines between \fBif\fR..\fBendif\fR only if
\fIpattern\fR matches (does not match). The \fBif\fR..\fBendif\fR
can nest.
Do not prepend whitespace to patterns inside \fBif\fR..\fBendif\fR.
.PP
Each pattern is a regular expression enclosed by a pair of delimiters.
The regular expression syntax is described in \fIre_format\fR(7).
The expression delimiter can be any character, except whitespace
or characters that have special meaning (traditionally the forward
slash is used). The regular expression can contain whitespace.
By default, matching is case-insensitive, although following
the second slash with an `i' flag will reverse this. Other flags
are `x' (disable extended expression syntax), and `m' (enable
multi-line mode, that is, treat newline characters as special).
Each pattern is applied to the entire lookup key string.
Depending on the application, that string is an entire client
hostname, an entire client IP address, or an entire mail address.
Thus, no parent domain or parent network search is done, and
\fIuser@domain\fR mail addresses are not broken up into their
\fIuser\fR and \fIdomain\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.
Substitution of substrings from the matched expression into the result
string is possible using $1, $2, etc.. The macros in the result string
may need to be written as ${n} or $(n) if they aren't followed
by whitespace.
.SH EXAMPLE SMTPD ACCESS MAP
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.nf
# Disallow sender-specified routing. This is a must if you relay mail
# for other domains.
/[%!@].*[%!@]/ 550 Sender-specified routing rejected
# Postmaster is OK, that way they can talk to us about how to fix
# their problem.
/^postmaster@/ OK
# Protect your outgoing majordomo exploders
if !/^owner-/
/^(.*)-outgoing@(.*)$/ 550 Use ${1}@${2} instead
endif
.SH EXAMPLE HEADER FILTER MAP
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.nf
# These were once common in junk mail.
/^Subject: make money fast/ REJECT
/^To: friend@public\\.com/ REJECT
.SH EXAMPLE BODY FILTER MAP
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# First skip over base 64 encoded text to save CPU cycles.
~^[[:alnum:]+/]{60,}$~ OK
# Put your own body patterns here.
.SH SEE ALSO
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pcre_table(5) format of PCRE tables
.SH AUTHOR(S)
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The regexp table lookup code was originally written by:
LaMont Jones
lamont@hp.com
That code was based on the PCRE dictionary contributed by:
Andrew McNamara
andrewm@connect.com.au
connect.com.au Pty. Ltd.
Level 3, 213 Miller St
North Sydney, NSW, Australia
Adopted and adapted by:
Wietse Venema
IBM T.J. Watson Research
P.O. Box 704
Yorktown Heights, NY 10598, USA