#++
# NAME
#	regexp_table 5
# SUMMARY
#	format of Postfix regular expression tables
# SYNOPSIS
#	regexp:/etc/postfix/filename
# DESCRIPTION
#	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.
#
#	The general form of a Postfix regular expression table is:
# .IP "\fIpattern result\fR"
#	When \fIpattern\fR matches a search string, use 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.
# .IP "\fIpattern1!pattern2 result\fR"
#	Matches \fIpattern1\fR but not \fIpattern2\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).
#
#	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 $(n) if they aren't followed
#	by whitespace.
# EXAMPLE SMTPD ACCESS MAP
#	# Disallow sender-specified routing. This is a must if you relay mail
#	# for other domains.
#	/[%!@].*[%!@]/	     550 Sender-specified routing rejected
#
#	# Postmaster is OK, that way they can talk to us about how to fix
#	# their problem.
#	/^postmaster@/	     OK
#
#	# Protect your outgoing majordomo exploders
#	/^(.*)-outgoing@(.*)$/!/^owner-/	 550 Use ${1}@${2} instead
# EXAMPLE HEADER FILTER MAP
#	# These were once common in junk mail.
#	/^Subject: make money fast/     REJECT
#	/^To: friend@public\\.com/	 REJECT
# SEE ALSO
#	pcre_table(5) format of PCRE tables
# 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
#--