[Dovecot] Filtering Mails - how?

[Daniel Seichter]

Hello,

I've got some problems about understanding, how to filter my incoming mails.
I am using dovecot 1.0.beta3 (ubuntu server) and want to implement a filter,
where I can filter all my incoming messages (like the ones from the dovecot
ml) to special folders within the mailbox of each user (for each user a
special set of filters).
Is there a chance to do this in dovecot or have I to use another program? 
My system works like:
Fetchmail fetches mails from two mailservers and deliver them to the users
inbox
Procmail send them to spamassassin for checking about spam
Dovecot provides access to the mailbox with IMAP

Hope there is an easy way like module for webmin or something else.

Thank you

Daniel