This article is the second and final installment describing my efforts to defend my systems from spam. The first article explains some necessary concepts and terminology. This article will dig more into the details of an actual implementation with my mail system. One thing to note is that I used qmail for my mail system (hence the title), but the information in here could apply to just about any email server in production today.

In the previous article, I covered the history and the protocol used by network level spam defenses but not the existing landscape of RBL Providers that supply blocklists. There are quite a few of them out there, and I needed to select one for my system. At first, I polled a few friends to see what they were doing. Most had tried a blocklist at some point. I found that some people mix various blocklists and usually don't trust them enough for their corporate machines. Some switch providers periodically since the quality isn't stable. One friend had to get new blocks of IP addresses for his service since he was in the same network block as a spammer. This form of collateral damage caused him to be very negative about the whole subject.

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