PCRE_TABLE(5)

NAME
pcre_table - format of Postfix PCRE tables

SYNOPSIS
pcre:/etc/postfix/filename

DESCRIPTION
The Postfix mail system uses optional tables for address rewriting or mail routing. These tables are usually in dbm or db format. Alternatively, lookup tables can be specified in Perl Compatible Regular Expression form. To find out what types of lookup tables your Postfix system supports use the postconf -m command. The general form of a PCRE table is:

blanks and comments
    Blank lines are ignored, as are lines beginning with `#'.

leading whitespace
    Lines that begin with whitespace continue the previous line.

pattern result
    When pattern matches a search string, use the corresponding result. A line that starts with white space continues the preceding line.

Each pattern is a perl-like regular expression. 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 supported, but the only other useful one is `U', which makes matching ungreedy (see PCRE documentation and source for more info). Each pattern is applied to the entire string being looked up. 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. Patterns are applied in the order as specified in the table, until a pattern is found that matches the search string. Substitution of sub-strings from the matched expression is possible using the conventional perl syntax ($1, $2, etc.). The macros in the replacement string may need to be written as ${n} or $(n) if they aren't followed by whitespace.

EXAMPLES
# Protect your outgoing majordomo exploders
/^(?!owner-)(.*)-outgoing@(my.domain)$/    550 Use ${1}@${2} instead
# Bounce friend@whatever, except when whatever is our domain (you would
# be better just bouncing all friend@ mail - this is just an example).
/^friend@(?!my.domain).*$/         550 Stick this in your pipe $0
# A multi-line entry. The text is sent as one line.
#
/^noddy@connect.com.au$/
 550 This user is a funny one. You really don't want to send mail to
 them as it only makes their head spin.

SEE ALSO
regexp_table(5) format of POSIX regular expression tables

AUTHOR(S)
The PCRE table lookup code was originally written 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