The Sysadmin’s Daily Grind: FuzzyOCR
The latest trend is to hide spam in images. The admin’s response: an OCR tool that extracts the texts and feeds them to the spam filter.
If you run Spamassassin, the Fuzzy-OCR plugin is a good choice of image evaluation tool. FuzzyOCR isn’t hard to install, except for having to fulfill a few dependencies. Make sure your version of Spamassassin is as up-to-date as possible; it should be anyway, of course, but version 3.1.4 is a must. You also need the NetPBM tools, from the Imagemagick convert binary, Giflib, two Perl modules, and gocr for optical character recognition.