Reason: Spamfilter-plugin for Claws Mail (and other mail-applications)
"Bogofilter is a mail filter that classifies mail as spam or ham (non-spam) by a statistical analysis of the message's header and content (body). The program is able to learn from the user's classifications and corrections."
Who needs: Claws Mail users.
Open source: GPL v2
Latest source: https://sourceforge.net/projects/bogofilter/files/latest/download (Sourceforge website)
Comment: it's a very old project, but still maintained. I love the possibility to softlink/move Bogofilter's wordlist database into the [own|next]cloud. So I can in fact use Claws Mail on different computers with different OSs (Ubuntu / Solus) with having an identical and well-working spamfilter for my imap mailbox.
Since Doxygen is now in unstable, packaging might be more easy....