Note to those of you using AOL as your ISP (I'm especially directing this to some members of my family) -- AOL has implemented an anti-spam strategy that relies on brute-force rather than intelligence. They are now dropping inbound mail based on the MAPS DUL, which is practically guaranteed to throw the baby out with the bath water. Because my IP address is in a DHCP range, AOL treats me as though I were Alan Ralsky or something, rather than a responsible admin who has never sent a single spam or allowed a spammer to relay using his resources.
At times like this, I really do wonder why the heck AOL bought Netscape. After all, the Mozilla project, the basis of the Netscape browser, has actually implemented intelligent spam filtering, and Apple has very successfully implemented latent semantic analysis in a widely deployed, real world mail client, so we're definitely outside the realm of theory here. Instead of putting these sorts of smarts to work in their client, AOL puts out press releases.
My recommendation to end-users is to go with an ISP who lets you decide
what's spam and what isn't, and provides you with intelligent tools that help
you block the mail that you want to. And if I owe you email and you haven't gotten it, maybe, just maybe, it wasn't my fault.
There are ten or twenty basic truths, and life is the process of
discovering them over and over and over.
— David Nichols