... to gross misspellings in order to get past the filters. There's got to be some way to key on that. %words not recognized or some such.

If you're talking about substituting numbers/symbols for letters, yes, they've been doing that for quite a long time. My filter generates a munged subject line (essentially tr/$1!|@-*./siiia/),chops out white space, and does a pattern match on that for the big three (viagra, xanax, cailis). However, if you're using SpamAssassin, it adds an "IMPOTENCE" keyword in the X-SpamAssassin header, so you can key off that even easier. Using a combination of those two (SpamAssassin doesn't seem to catch everything), I'm now getting maybe one, or two spam slip through every few days. Don't know how you'd do that via Outlook/Mozilla/whatever.

Quote:
%words not recognized or some such.

It's been suggested before. Spammers are now adding a random collection of proper 'non-spam' words to the bottom of spam messages to counter this counter.

A decent Baysian based spam filter is not fooled by these two tactics. Only a handful of spam get into my inbox, even though I am receiving many hundreds of spam messages a day.