I give up. Thunderbird, as great as it is at classifying spam, just isn't good enough to combat the all the crap that fills my inbox. It probably only catches %80 of the spam that comes my way, and that's pretty bad when I get 50-100 spams a day.
Why so much spam? It's pretty simple. Just go and register any domain. Set up a catch-all for @yourdomain.com to point to an account, and watch the spam come in.... for everyone. Susie, Ron, Bob, Jack, Tom, Tim, Phil, and of course, John. If it's a common name, you'l get email for it at firstname.lastname@example.org. Spammers guess at all sorts of common names to try to find new targets for their herbal viagra ads and genital enlargment creams.
This has become a problem for my email address. John is a pretty common name after all. But really, few people actually email me there. I've taken to creating a new email address for each entity I share my contact info with. I've prepared for this by creating a catchall for the subdomain of @john.mydomain.com For instance, if I share my address with Joe Blo, I ask him to email me at email@example.com. If his computer ever gets compromised, or he decides to share this address with spammers, I simply tell sendmail to start rejecting this address.
Other than the fact that i've been still accepting mail for john@, It's been working pretty well. The only people who have emailed me directly are family members and spammers. So I've told family to start using a sub-domained address and told sendmail to start rejecting firstname.lastname@example.org.
So that's it. I give up. You've ruined my uber-slick email address, so I must reject all of your mail and move on to a less convenient address.