PCRE_TABLE(5)                                                    PCRE_TABLE(5)

       pcre_table - format of Postfix PCRE tables

       postmap -q "string" pcre:/etc/postfix/filename

       postmap -q - pcre:/etc/postfix/filename <inputfile

       postmap -hmq - pcre:/etc/postfix/filename <inputfile

       postmap -bmq - pcre:/etc/postfix/filename <inputfile

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

       Alternatively,  lookup tables can be specified in Perl Compatible Regu-
       lar 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)  pat-
       terns,  and  "postmap -bmq - <file" for body_checks(5) (Postfix 2.6 and

       This driver can be built  with  the  pcre2  library  (Postfix  3.7  and
       later), or with the legacy pcre library (all Postfix versions).

       With  Postfix  version 2.2 and earlier specify "postmap -fq" to query a
       table that contains case sensitive patterns. Patterns are case insensi-
       tive by default.

       The general form of a PCRE 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  corre-
              sponding 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 perl-like regular expression. The expression delim-
       iter can be any non-alphanumeric character, except whitespace or  char-
       acters  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

       i (default: on)
              Toggles  the case sensitivity flag. By default, matching is case

       m (default: off)
              Toggles the pcre MULTILINE 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 subject string.

       s (default: on)
              Toggles  the  pcre  DOTALL  flag.  When  this  flag is on, the .
              metacharacter matches the newline character. With  Postfix  ver-
              sions  prior to 2.0, the flag is off by default, which is incon-
              venient for multi-line message header matching.

       x (default: off)
              Toggles the pcre extended flag. When this flag is on, whitespace
              characters  in the pattern (other than in a character class) are
              ignored.  To include a whitespace character as part of the  pat-
              tern, escape it with backslash.

              Note: do not use #comment after patterns.

       A (default: off)
              Toggles  the pcre ANCHORED flag.  When this flag is on, the pat-
              tern is forced to be "anchored", that is, it is  constrained  to
              match  only  at  the start of the string which is being searched
              (the "subject string"). This effect  can  also  be  achieved  by
              appropriate constructs in the pattern itself.

       E (default: off)
              Toggles  the pcre DOLLAR_ENDONLY flag. When this flag is on, a $
              metacharacter in the pattern matches only at the end of the sub-
              ject  string.  Without  this flag, a dollar also matches immedi-
              ately before the final character if it is  a  newline  character
              (but  not  before  any  other  newline characters). This flag is
              ignored if the pcre MULTILINE flag is set.

       U (default: off)
              Toggles the pcre UNGREEDY flag.  When this flag is on, the  pat-
              tern matching engine inverts the "greediness" of the quantifiers
              so that they are not greedy by default,  but  become  greedy  if
              followed  by  "?".   This  flag  can also set by a (?U) modifier
              within the pattern.

       X (default: off)
              Toggles the pcre EXTRA flag.  When this flag is  on,  any  back-
              slash in a pattern that is followed by a letter that has no spe-
              cial meaning causes an error, thus reserving these  combinations
              for future expansion.

              This feature is not supported with PCRE2.

       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  par-
       ent network search is done, and user@domain mail addresses are not bro-
       ken up into their user and domain constituent parts,  nor  is  user+foo
       broken up into user and foo.

       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.   This feature does not support
       pcre2 substring names.

       Note: since negated patterns (those preceded by !) return a result when
       the  expression  does  not  match,  substitutions are not available for
       negated patterns.

       The contents of a table may be specified in the table name (Postfix 3.7
       and later).  The basic syntax is:

           parameter = .. pcre:{ { rule-1 }, { rule-2 } .. } ..

           .. -o { parameter = .. pcre:{ { rule-1 }, { rule-2 } .. } .. } ..

       Postfix  ignores  whitespace  after '{' and before '}', and writes each
       rule as one text line to an in-memory file:

       in-memory file:

       Postfix parses the result as if it is a file in /etc/postfix.

       Note: if an inlined rule contains $, specify $$ to  keep  Postfix  from
       trying to do $name expansion as it evaluates a parameter value.

       Note: when using $name inside an inlined pattern, use \Q$name\E to dis-
       able metacharacters such as '.' in the $name expansion. Otherwise,  the
       pattern may have unexpected matches.

       # Protect your outgoing majordomo exploders
       /^(?!owner-)(.*)-outgoing@(.*)/ 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 $1

       # A multi-line entry. The text is sent as one line.
        550 This user is a funny one. You really don't want to send mail to
        them as it only makes their head spin.

       /^Subject: make money fast/     REJECT
       /^To: friend@public\.com/       REJECT

       # First skip over base 64 encoded text to save CPU cycles.
       # Requires PCRE version 3.
       ~^[[:alnum:]+/]{60,}$~          OK

       # Put your own body patterns here.

       postmap(1), Postfix lookup table manager
       postconf(5), configuration parameters
       regexp_table(5), format of POSIX regular expression tables

       DATABASE_README, Postfix lookup table overview

       The PCRE table lookup code was originally written by:
       Andrew McNamara
       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