Spam filtering support with Procmail+Bogofilter

I recently set up procmail+bogofilter to help me weed out spam that mail providers can't deal with.

@LukeSmithxyz would you be interested in merging such a contribution?

It does its thing for me locally but making it general purpose would take more work (in particular Inbox/INBOX trips it up) so thought best to ask before I do that.