How to get rid of all the spam ?

Recently the Kdenlive forums seem to be overwhelmed by spam, bumping up old threads (sometimes actually digging up useful forgotten topics...) with meaningless posts.

Quite a lot of these spam posts aren't even bots, so captchas won't work (and there already is a captha when you create a new account).

Is there a know way to actually get rid of them ? As soon as I see such a post I "flag as offensive", but I don't know how well that works.