I'm running SpamAssassin 3.1.0 with sendmail, and I think it's great.
I'm using milter-spamc to interface with SpamAssassin running as a daemon.
It doesn't /quite/ catch everything, and some (very little, actually)
SPAM gets through untagged.
I spent some time looking at the SPAM and compared it it to the
legitimate email I receive.
On a large percentage of the SPAM that gets through, the only Received:
header that exists was put there by my mailserver.
The legitimate email, on the other hand ALL has at least one additional
Received: header, OR the machine it was received from is allowed to
relay mail through the mailserver. (either via an entry in the access
database, or because the IP or machine name matches a line in
/etc/mail/relay_domains.
So, I was wondering if the following set of logic would be possible to
implement in SpamAssassin, either as a collection of rules, or a plugin:
IF:
The number of Received headers == 0
AND
Client Server's IP is NOT in /etc/mail/relay_domains (or equivalent)
AND
Client Server does NOT have an entry in access_db allowing it to
relay mail
THEN:
Increase the spam score of the email by a significant amount.
ELSE:
Do nothing. (go to the next rule)
Thanks.
