Mail filtering using procmail are there other alternatives?

[Adi Linden]

Our mail server currently uses the sendmail MTA and cyrus-imap. Sendmail 
passes mail for local delivery to /var/imap/socket/lmtp

I need to be able to filter mail. Is there a way to patch procmail into 
the process to use it to filter mail?

Are there any other means to use filtering with cyrus-imap? The server 
doesn't have user accounts. How could I facilitate filters that individual 
users could manage, such as a vacation message?

Thanks,
Adi