The spam overflow that has hit inboxes is a result of a reinterpretation of a technique called image-based spam, that comprises all the content inside graphics, and bypassing spam filters. As they contain little to no text at all, traditional content and signature analysis methods fail to tag image spam as what it really lets it through enterprise and Internet Services Provider's anti-spam filters.

E-mail security vendor IronPort has released a study according to which, in June 2006, 12 percent of all spam was represented by image-based spam. This data is equivalent to a growth of 1.200% since June 2005. CipherTrust, another security firm has reported and even higher percentage, at 15%.

"While using images in spam is not a new concept, changing the image in real-time in each delivered spam message is a relatively new capability that the spammers have been able to acquire," said Dmitri Alperovitch, research scientist with CipherTrust. "This is due to the development and release of the new high-performance software marketed in the underground markets that is able to randomize images in a very high-performance fashion and allow spammers to send millions of them every hour."

IronPort has warned that the randomizing technique creates unique spam messages and makes their detection and filtering virtually impossible.