Mail filtering using procmail are there other alternatives?

[Adi Linden]

> Cyrus supports server-side filtering via Sieve.  This includes filing 
> messages into folders, vacation responses, and more.  Read the docs for 
> details.  There are a handful of Web interfaces (eg, Websieve) for 
> managing scripts.

Ok, but what about spam detection tools that rely on procmail recipes? I 
read the sample chapter from an O'Reilly book that's online and describes 
how to integrate sendmail, procmail and cyrus-imap:

    http://www.oreilly.com/catalog/mimap/chapter/ch09.html

Does this work fine in cases where cyrus-imap fails to deliver the message 
due to over quota or non existant mailboxes?

Thanks,
Adi