Squirrelmail, avelsieve, Dovecot, where's the autoresponder thingy?

[aseques]

I haven't look at that yet, but, if you want to install avelsieve, you will need a sieve server somewhere.
Since you are not using courier now, you'll have to use a replacement. I've found two different ones being the first one the one that worked:
.- http://www.woozle.org/~neale/src/pysieved/ -> Standalone python sieve server, just arrange the .ini as explained somewhere in this forums (ispcp) and will be working
.- http://wiki.dovecot.org/ManageSieve -> It's a patch versus dovecot code, it might be included in Ubuntu Hardy (not sure about that), otherwise you'll have to patch / compile the code.