Spammers are nothing if not clever. Realizing that the increased sensitivity threshold of filters was thwarting their attempts, they turned to a different, more elusive, spamming method: image spam.

Image spam—e-mail solicitations that use graphical images of text—is not new. But its rising sophistication has made much of it invisible to spam filters so that it makes up one-third of all spam, ...

An email advertisement in the form of an image in the message rather than text in order to avoid detection as spam. Spam filters typically analyze words in a message, which is relatively fast, but ...