Spam, spam, spam
After living with 100s of emails per day that got around spamassassin and blacklists (they tend to have subjects and text that l00k l!ke th!s), I finally gave up and followed everyone else's lead to Knowspam. The weirdest part about it, now that it is in place, is getting 4 or 5 emails when I woke up today, instead of having to wade through 150 (mostly bogus) messages every morning.
I never wanted to retreat to a whitelist situation, but it seems to work too good already and I'm sticking with it.