REGEXP_TABLE(5) File Formats Manual REGEXP_TABLE(5)
NAME
regexp_table - format of Postfix regular expression tables
SYNOPSIS
postmap -q "string" regexp:/etc/postfix/filename
postmap -q - regexp:/etc/postfix/filename <inputfile
DESCRIPTION
The Postfix mail system uses optional tables for address rewriting, mail routing, or access control. These
tables are usually in dbm or db format.
Alternatively, lookup tables can be specified in POSIX regular expression form. In this case, each input is
compared against a list of patterns. When a match is found, the corresponding result is returned and the
search is terminated.
To find out what types of lookup tables your Postfix system supports use the "postconf -m" command.
To test lookup tables, use the "postmap -q" command as described in the SYNOPSIS above.
COMPATIBILITY
With Postfix version 2.2 and earlier specify "postmap -fq" to query a table that contains case sensitive pat‐
terns. Patterns are case insensitive by default.
TABLE FORMAT
The general form of a Postfix regular expression table is:
/pattern/flags result
When pattern matches the input string, use the corresponding result value.
!/pattern/flags result
When pattern does not match the input string, use the corresponding result value.
if /pattern/flags
endif Match the input string against the patterns between if and endif, if and only if that same input string
also matches pattern. The if..endif can nest.
Note: do not prepend whitespace to patterns inside if..endif.
This feature is available in Postfix 2.1 and later.
if !/pattern/flags
endif Match the input string against the patterns between if and endif, if and only if that same input string
does not match pattern. The if..endif can nest.
Note: do not prepend whitespace to patterns inside if..endif.
This feature is available in Postfix 2.1 and later.
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
i (default: on)
Toggles the case sensitivity flag. By default, matching is case insensitive.
m (default: off)
Toggle the multi-line mode flag. When this flag is on, the ^ and $ metacharacters match immediately
after and immediately before a newline character, respectively, in addition to matching at the start
and end of the input string.
x (default: on)
Toggles the extended expression syntax flag. By default, support for extended expression syntax is
enabled.
TABLE SEARCH ORDER
Patterns are applied in the order as specified in the table, until a pattern is found that matches the input
string.
Each pattern is applied to the entire input 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 user@domain mail addresses are not broken up into their user and domain con‐
stituent parts, nor is user+foo broken up into user and foo.
TEXT SUBSTITUTION
Substitution of substrings from the matched expression into the result string is possible using $1, $2, etc.;
specify $$ to produce a $ character as output. The macros in the result string may need to be written as ${n}
or $(n) if they aren't followed by whitespace.
Note: since negated patterns (those preceded by !) return a result when the expression does not match, substi‐
tutions are not available for negated patterns.
EXAMPLE SMTPD ACCESS MAP
# Disallow sender-specified routing. This is a must if you relay mail
# for other domains.
/[%!@].*[%!@]/ 550 Sender-specified routing rejected
# Postmaster is OK, that way they can talk to us about how to fix
# their problem.
/^postmaster@/ OK
# Protect your outgoing majordomo exploders
if !/^owner-/
/^(.*)-outgoing@(.*)$/ 550 Use ${1}@${2} instead
endif
EXAMPLE HEADER FILTER MAP
# These were once common in junk mail.
/^Subject: make money fast/ REJECT
/^To: friend@public\.com/ REJECT
EXAMPLE BODY FILTER MAP
# First skip over base 64 encoded text to save CPU cycles.
~^[[:alnum:]+/]{60,}$~ OK
# Put your own body patterns here.
LaMont Jones
[email protected]
That code was based on the PCRE dictionary contributed by:
Andrew McNamara
[email protected]
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
REGEXP_TABLE(5)
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