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REGEXP_TABLE(5)                                                REGEXP_TABLE(5)

       regexp_table - format of Postfix regular expression tables

       <b>postmap -q "</b><i>string</i><b>" <a href="regexp_table.5.html">regexp</a>:/etc/postfix/</b><i>filename</i>

       <b>postmap -q - <a href="regexp_table.5.html">regexp</a>:/etc/postfix/</b><i>filename</i> &lt;<i>inputfile</i>

       The Postfix mail system uses optional tables  for  address
       rewriting,  mail  routing, or access control. These tables
       are usually in <b>dbm</b> or <b>db</b> format.

       Alternatively, lookup tables can  be  specified  in  POSIX
       regular  expression form. In this case, each input is com-
       pared against a list of patterns. When a match  is  found,
       the  corresponding  result  is  returned and the search is

       To find out what types of lookup tables your Postfix  sys-
       tem supports use the "<b>postconf -m</b>" command.

       To  test  lookup  tables,  use the "<b>postmap -q</b>" command as
       described in the SYNOPSIS above.

       With Postfix version 2.2 and earlier specify "<b>postmap -fq</b>"
       to  query  a  table that contains case sensitive patterns.
       Patterns are case insensitive by default.

       The general form of a Postfix regular expression table is:

       <b>/</b><i>pattern</i><b>/</b><i>flags result</i>
              When <i>pattern</i> matches the input string, use the cor-
              responding <i>result</i> value.

       <b>!/</b><i>pattern</i><b>/</b><i>flags result</i>
              When <i>pattern</i> does <b>not</b> match the input  string,  use
              the corresponding <i>result</i> value.

       <b>if /</b><i>pattern</i><b>/</b><i>flags</i>

       <b>endif</b>  Match the input string against the patterns between
              <b>if</b> and <b>endif</b>, if and only if that same input string
              also matches <i>pattern</i>. The <b>if</b>..<b>endif</b> can nest.

              Note:  do not prepend whitespace to patterns inside

              This feature is available in Postfix 2.1 and later.

       <b>if !/</b><i>pattern</i><b>/</b><i>flags</i>

       <b>endif</b>  Match the input string against the patterns between
              <b>if</b> and <b>endif</b>, if and only if that same input string
              does <b>not</b> match <i>pattern</i>. The <b>if</b>..<b>endif</b> can nest.

              Note:  do not prepend whitespace to patterns inside

              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  logi-
              cal line.

       Each  pattern  is a POSIX regular expression enclosed by a
       pair of delimiters. The regular expression syntax is docu-
       mented  in  <b>re_format</b>(7)  with  4.4BSD,  in  <b>regex</b>(5) with
       Solaris, and in <b>regex</b>(7) with Linux. Other systems may use
       other document names.

       The  expression  delimiter  can  be  any character, except
       whitespace or characters that have special meaning (tradi-
       tionally  the  forward slash is used). The regular expres-
       sion can contain whitespace.

       By default, matching is case-insensitive, and newlines are
       not  treated  as  special characters. The behavior is con-
       trolled by flags, which are toggled by  appending  one  or
       more of the following characters after the pattern:

       <b>i</b> (default: on)
              Toggles  the  case  sensitivity  flag.  By default,
              matching is case insensitive.

       <b>m</b> (default: off)
              Toggle the multi-line mode flag. When this flag  is
              on,  the  <b>^</b>  and <b>$</b> metacharacters match immediately
              after and immediately before a  newline  character,
              respectively,  in addition to matching at the start
              and end of the input string.

       <b>x</b> (default: on)
              Toggles the extended  expression  syntax  flag.  By
              default,  support for extended expression syntax is

       Patterns are applied in the order as specified in the  ta-
       ble,  until  a  pattern  is  found  that matches the input

       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 <i>user@domain</i>  mail  addresses  are  not
       broken  up  into  their <i>user</i> and <i>domain</i> constituent parts,
       nor is <i>user+foo</i> broken up into <i>user</i> and <i>foo</i>.

       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 <b>!</b>)  return
       a result when the expression does not match, substitutions
       are not available for negated patterns.

       # 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

       # These were once common in junk mail.
       /^Subject: make money fast/     REJECT
       /^To: friend@public\.com/       REJECT

       # First skip over base 64 encoded text to save CPU cycles.
       ~^[[:alnum:]+/]{60,}$~          OK

       # Put your own body patterns here.

<b>SEE ALSO</b>
       <a href="postmap.1.html">postmap(1)</a>, Postfix lookup table manager
       <a href="pcre_table.5.html">pcre_table(5)</a>, format of PCRE tables
       <a href="cidr_table.5.html">cidr_table(5)</a>, format of CIDR tables

       <a href="DATABASE_README.html">DATABASE_README</a>, Postfix lookup table overview

       The regexp table lookup code was originally written by:
       LaMont Jones

       That code was based on the PCRE dictionary contributed by:
       Andrew McNamara 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

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