Try some links at here, try the section ‘Spam Tools’. Maybe some of them:
File13
Mail Washer
SpamPal
You´ll find MailWasher useful if you have just one email account. For more than one, you must buy MailWasher(Pro).
Edit: If anybody wants to configure Spamihilator and avast! to be used in the same computer, please, see this related forum.