REGEXP_TABLE(5)                                   REGEXP_TABLE(5)

          regexp_table - format of Postfix regular expression tables

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

          postmap -q - regexp:/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 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

          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).

          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.

          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

               If the input string matches /pattern/, then match  that
               input string against the patterns between if and endif.
               The if..endif can nest.

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     REGEXP_TABLE(5)                                   REGEXP_TABLE(5)

               Note: do not  prepend  whitespace  to  patterns  inside

               This feature is available in Postfix 2.1 and later.

          if !/pattern/flags

               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

               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.

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     REGEXP_TABLE(5)                                   REGEXP_TABLE(5)

          x (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 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.

          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.

          # 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

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     REGEXP_TABLE(5)                                   REGEXP_TABLE(5)

          # Put your own body patterns here.

          postmap(1), Postfix lookup table manager
          pcre_table(5), format of PCRE tables
          cidr_table(5), format of CIDR tables

          Use "postconf readme_directory" or "postconf html_directory"
          to locate this information.
          DATABASE_README, 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

          Wietse Venema
          Google, Inc.
          111 8th Avenue
          New York, NY 10011, USA

     Page 4                       Plan 9             (printed 5/26/22)