Experimental: check_header

How to install

1. You need map-regex Version 2.7 or later. If you want to use the Option _FRIEND_STORAGE_, move map_storage.c to sendmail-?.?.?/src and compile with OBJADD=map_storage.o, DBMDEF= -DMAP_STORAGE ...
2. Apply the patch (headers.c.patch) to sendmail-8.8.?/src/headers.c
3. Edit conf.h: Enlarge the size of MAXNAME to 2048, MAXATOM to 1024. This is needed for long Received-lines and cc-lines.

   #define MAXNAME        2048            /* max length of a name */
   #define MAXATOM        1024             /* max atoms per address */
   

4. Edit your Makefile in sendmail-8.8.?/src/Makefiles/

   O= ... -D_FFR_HEADER_RSCHECK ...
   

5. Edit parseaddr.c, find rscheck() and comment out the syserr:

           if (pvp == NULL)
           {
           /*
                   syserr("rscheck: cannot prescan input: \"%s\"",
                           shortenstring(buf, 203));
                   rstat = EX_DATAERR;
           */
                   goto finis;
           }
   ./makesendmail clean; ./makesendmail
   copy check_header.m4 to sendmail-8.8.?/cf/hack
   edit your .mc-file
   ...
   dnl * put options here i.e. *
   define(`_CHECK_HEADER_RECEIVED_', `1')dnl
   define(`_CHECK_HEADER_FROM_', `1')dnl
   define(`_CHECK_HEADER_REPLY_TO_', `1')dnl
   dnl * this is an experimental hack, i use it at my own risk *
   HACK(check_header)
   ...
   
   send feedback to 
   Jan.Krueger+map@stud.uni-hannover.de
   

Options for check_header.m4

_MAPS_RBL_
Make use of Paul Vixie's RBL.

_FRIEND_STORAGE_ (recommended) (see "known Problems")
Use the map-storage for spam_friends. Don't filter their mail. Compile sendmail with DBMDEF= ... -DMAP_STORAGE ... Assign the storage map in your check_rcpt, e.g.:

Scheckrcpt
# allow some local addresses; use only legal syntax
R<$+@$=w>               $: <$(spam_friends $1 $) @ $2>
R<$+@SPAMFRIEND@$=w>    $@ $(friend YES $)

_X_SPAM_HEADER_
Don't return an error, if check_header detects a spam, but set the header-field X-Spam-Header: for later processing (i.e. with procmail). Needs v2.5 or later.

_CHECK_HEADER_FROM_
Check the address given in the From:-line of the header against junk.db This option is needed for the following, because it activates the ruleset check_from.

_CHECK_HEADER_REPLY_TO_
Check the address given in the Reply-To:-line of the header against junk.db. Uses the ruleset check_from.

_CHECK_HEADER_SENDER_
Check the address given in the Sender:-line of the header against junk.db. Uses the ruleset check_from.

_CHECK_HEADER_TO_
Check the address given in the To:-line of the header against junk.db. Uses the ruleset check_from.

_CHECK_HEADER_CC_
Check the address given in the Cc:-line of the header against junk.db. Uses the ruleset check_from.

_CHECK_HEADER_MESSAGE_ID_
Check the Message-Id (rfc822).

Check_header needs the rulesets junk and junkIP. They are included in "Using check_* in sendmail 8.8" by Claus Aßmann.

The parse_received pattern can parse the following formats (host = hostname or [ip]):

from host
from host (1.2.3.4)
from host ([1.2.3.4])
from host (user@host)
from host (hostname [1.2.3.4])
from host (hostname[1.2.3.4])
from host (keyword hostname [1.2.3.4])
(from user@localhost) is not matching

What is the patch doing?

HFname: $>check_ruleset
HFname: $>"check_ruleset (encapsulate the value in "")
HFname: $>$|check_ruleset (normal and encapsulated value seperated by $|)

Scheck_ruleset
...