I was wondering the web looking at random items, when I came along an article at http://www.worldwidecreations.com titled Stopping spam before the door with SpamCop and IPTables
Its a great article with a lot of information and code on how the author is able to grab the offending hosts and place them within IPTables.
One thing that I really can’t agree with is the use of IPTables to block mail traffic from an RBL that has in the past and present block many legitimate hosts and email. I’d rather have spam to my account marked as spam so that I can be the judge and correct any false positives. At the moment, all my mail using using Exim with sa-exim (SMTP time spamassassin scanning). This allows for messages to be bounced back at SMTP time!
What is everyone else using for an MTA and how are you filtering spam?