I've recently setup a mailserver with dovecot and stumbled upon the lda/sieve plugin (
http://wiki.dovecot.org/LDA/Sieve) which lets me do server-side filtering.
At first I just used it to move the detected spam mails to a folder, but then played with it a bit. Now i have about 200 lines of rules increasing every day. I really like the idea of sorting the emails without having to configure rules for every mail client i use.
With all the hacking going on here I started to think it would be a nice thing to enable creating and editing of those rules to my virtual users. I'd really like to do it myself and will definitely look into it - and if so, will post my results here - but right now i'm pretty fed up with my daily administration jobs.
So, i'm putting this idea out here in the wild. Perhaps someone with a little bit more than my php experience feels enthusiastic about it, too.
Just because this is my first post here, i'd like to say thank you all for doing such a nice job with maintaining and enhancing RoundCube.