FuzzyOcr is a plugin for SpamAssassin written by Christian Holler and Jorge Valdes, distributed under the Apache License v.2.0, and is currently being distributed as a package by Linux distros such as Debian.
I am neither of the creators; please do give credit to who credit is due.
My main contribution is that I found out reading the spamassassin mailing list that it is unmaintained. Further investigation told me the last release of FuzzyOcr was 3.6.0. Using the wayback machine, I found a 2012 page from its original wiki, http://fuzzyocr.own-hero.net/ (site has been down for a while; expect one day the Nigerian Prince will snatch it), stating that
This project is UNMAINTAINED as of 2009-06-01. Use it at your own risk. If you want to fork this project, drop me a note (decoder[at]own-hero.net).
So, I requested permission to post the source code (I know, I know, Apache License v.2.0, but I like to pretend I am civilized, perhaps even having table manners) and that was granted. Then I found a tarball with its source code, grabbed it, and placed it here hoping that will allow others to continue developing/upgrading it.
As I have time I will copy the wiki and place it here.