>>> In Gnus, I want to be able to mark spam in INBOX with $, and ham in
>>> mail.spam with M-u, and have each moved to the right place.
>> I do exactly that. Here're the relevant settings:
> Your setting only move Spam around, they don't truly process it.
Oh, right. I just put false positives/negatives into some special
groups, and then update the spam handling tools on the servers regularly
via their web interfaces.