Spam prevention is not strictly a security problem, or if you choose to frame it that way it is entirely unlike most other system security challenges. Almost al

Spam prevention is not strictly a security problem, or if you choose to frame it that way it is entirely unlike most other system security challenges. Almost all spam prevention systems have some sort of secret sauce involved, otherwise spammers could train their own systems against it to discover what works. In other words, this is why most open-source security products are extremely competitive with (if not outright better than) their closed-source counterparts, but open-source spam prevention systems (with no disrespect to the people who work hard on them, because as I said, it's a hard problem) suck.