LXer: This week at LWN: Fighting image spam
 

Published at LXer:

A number of spammers have been evading filters like SpamAssassin (SA) recently by encoding their messages as images. SA already has a set of rules that are meant to combat image spam, but the more recent messages (typically for stock scams or pharmacy products) have been crafted to avoid them. This would indicate, once again, that spammers are using SA to pre-test their messages and are modifying them to get through. SA developers, however, are up to the challenge and two specific countermeasures have been released.

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