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. Use "
postmap -hmq -
<
file" for header_checks(5) patterns, and "
postmap
-bmq - <
file" for body_checks(5) (Postfix 2.6 and later).
COMPATIBILITY
With Postfix version 2.2 and earlier specify "
postmap
-fq" to query a table that contains case sensitive patterns.
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
- If the input string matches /pattern/, then match
that input string against the patterns between if and endif.
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
- If the input string does not match /pattern/, then
match that input string against the patterns between if and
endif. 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
- A logical line starts with non-whitespace text. A line that
starts with whitespace continues a logical line.
Each pattern is a POSIX regular expression enclosed by a pair of delimiters. The
regular expression syntax is documented in
re_format(7) with 4.4BSD, in
regex(5) with Solaris, and in
regex(7) with Linux. Other systems
may use other document names.
The expression delimiter can be any non-alphanumerical 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, and newlines are not treated as
special characters. The behavior is controlled by flags, which are toggled by
appending one or more of the following characters after the pattern:
- 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 constituent parts, nor is
user+foo
broken up into
user and
foo.
TEXT SUBSTITUTION
Substitution of substrings (text that matches patterns inside "()")
from the matched expression into the result string is requested with $1, $2,
etc.; specify $$ to produce a $ character as output. The macros in the result
string may need to be written as ${n} or $(n) if they aren't followed by
whitespace.
Note: since negated patterns (those preceded by
!) return a result when
the expression does not match, substitutions are not available for negated
patterns.
EXAMPLE SMTPD ACCESS MAP
# Disallow sender-specified routing. This is a must if you relay mail
# for other domains.
/[%!@].*[%!@]/ 550 Sender-specified routing rejected
# Postmaster is OK, that way they can talk to us about how to fix
# their problem.
/^postmaster@/ OK
# Protect your outgoing majordomo exploders
if !/^owner-/
/^(.*)-outgoing@(.*)$/ 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.
SEE ALSO
postmap(1), Postfix lookup table manager
pcre_table(5), format of PCRE tables
cidr_table(5), format of CIDR tables
README FILES
Use "
postconf readme_directory" or "
postconf
html_directory" to locate this information.
DATABASE_README, Postfix lookup table overview
AUTHOR(S)
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
Wietse Venema
Google, Inc.
111 8th Avenue
New York, NY 10011, USA