Get to your local CPAN mirror and install Mail::SpamAssassin::SpamCopURI. It looks up all URIs from the message and checks them against the Spam URI Realtime Blocklist ("Spamvertised sites" reported to SpamCop). I'm getting hits on about 30-40% of my spam.
Mail::SpamAssassin::SpamCopURI 0 Comments More | Login | Reply /