Virus Bounce Ruleset
There's a ruleset to block joe-job, virus-blowback, and spam-blowback bounce messages (a.k.a. "backscatter"), which hopefully will be included in SpamAssassin 3.2.0. In the meantime, if you are using SA 3.1.x, you can install it as follows:
Download [http://svn.apache.org/viewvc/spamassassin/rules/trunk/sandbox/jm/20_vbounce.cf?revision=482200&pathrev=482207 20_vbounce.cf] and [http://svn.apache.org/viewvc/spamassassin/rules/trunk/sandbox/jm/VBounce.pm?revision=467392&pathrev=482207 VBounce.pm] from jm's rules sandbox.
2. Save both files to your /etc/mail/spamassassin directory.
3. Edit your local.cf and add a line like the following:
whitelist_bounce_relays myrelay.mydomain.net
Replace myrelay.mydomain.net with the hostname of the relay (or relays) that you send your outbound mail through.
This is used to 'rescue' legitimate bounce messages that were generated in response to mail you really *did* send. If a bounce message is found, and it contains one of these hostnames in a 'Received' header, it will not be marked as a blowback virus-bounce.
4. Run spamassassin --lint and ensure it works.
5. Check a 'sample vbounce' mail, to ensure it marks blowback bounces as such:
spamassassin -Lt < sample-vbounce.txt [...] Content analysis details: (2.6 points, 5.0 required) pts rule name description ---- ---------------------- -------------------------------------------------- 0.0 NO_REAL_NAME From: does not include a real name 0.0 FORGED_RCVD_HELO Received: contains a forged HELO [...] 0.1 BOUNCE_MESSAGE MTA bounce message 0.1 ANY_BOUNCE_MESSAGE Message is some kind of bounce message
You should see the tests BOUNCE_MESSAGE and ANY_BOUNCE_MESSAGE appearing in the "Content analysis details" section.
5. Restart spamd, as usual, so that the ruleset is loaded.
Don't forget – once SpamAssassin 3.2.0 is released, you may need to delete VBounce.pm and 20_vbounce.cf from /etc/mail/spamassassin, so that it doesn't clash with the released version.