The only false positives I've experienced was when I accidentally
marked one "mod_perl digest" as SPAM.
It took about 5 trips to the SPAM folder to click "NOT SPAM" to start recieving the digest in my inbox again.
The onl things that slip past are
bounce-backs, very annoying and the filter seems to filter them like other spam, instead of checking that the original sender is *.mail.yahoo.com, not some russian website.
new nigerian 419 variations, but those are sooo easy to pick-off
MJDsays "you can't just make shit up and expect the computer to know what you mean, retardo!"