Overlay Spam

There's a new breed of spam that's beating the gmail filter 10% of the time.

The idea is to take some "real" text and make that the body of the email. The text probably comes from sites like Project Gutenberg. Then emit an image positioned over the text with opaque background color. The image contains the real advertisement.

The "good text" makes it past spam filters, then your client overlays that with the image.

UPDATE Sep 5 06: An article on LifeHacker how to filter these out of gmail.