The latest/greatest incarnation of my procmail filter at...
http://www.interlog.com/~waltdnes/spamdunk/spamdunk.htm
Additions June 10;
- attempt to trap spam coming in via open 3rd-party relays.
As part of the process, I also had to tighten up checking
of the "Message-Id:" header.
- check for spam with forged from headers, slandering
certain popular email services. You can add additional
names to the list if you wish.
- additional checking to trap RFMS/relay spam originating
from Compuserve dialup lines.
- rejection diagnostics are now inserted as "X-Reject:"
custom headers.
Change June 13;
- added a user-settable variable "SLACK" to cut some slack
in the checking. Basically, this variable tells procmail
how many "X-Reject:" flags can be added without junking
an email. If you set SLACK=0, then failing any of 11
recipies will junk an email. I find that almost all spam
fails at least two or three of the tests, so I recommend
running with SLACK=1 to minimize the chances of false
positives. The higher you set SLACK, the more stuff will
get through.
A detailed explanation of my filters is available at...
http://www.interlog.com/~waltdnes/spamdunk/techie.htm
--
Walter Dnes (Toronto)
<waltdnes(_at_)interlog(_dot_)com>