Here are some techniques spammers use to sneak advertisements past spam filters. They were compiled by computer security expert John Graham-Cumming, who came up with the names:
YOU'VE BEEN FRAMED: Using the $noframes$ tag, the spammer hides text and breaks up words. Example: Via$frame$$noframes$ywl55
$/noframes$$/frame$gra
NO WHITESPACE NO CRY: Spam filters recognize words by the spaces between them, so spammers remove the spaces. Example: NoPrescriptionRequired! (Graham-Cumming calls this one "dumb.")
SPEAKING IN TONGUES: Large nonsense words are used to confuse the filters. Example: ephaswukutugucrovazichonixisluwephimajoq.
ZE FOREIGN ACCENT: Replaces letters with numbers or uses nonsense accents. Example: V1DE0 T4PE M0RTG4GE
