Hi,
I stumbled upon your project while searching for an alternative for
https://getpopfile.org/docs/welcome
https://en.wikipedia.org/wiki/POPFile
Unfortunately this project was abandoned many years ago.
You specify categories in Popfile and it learns as you classify your e-mails.
It is working very well. You get at least a 95% correct classification.
Maybe this would be a good addition to your maildaemon?
Regards
Hyper