Avast Internet Security - Antispam doesn't work

Internet Security 6.0
Version: 6.0.1289
Mail client: The Bat
Protocols used: IMAPS (993), SMTPS (465)

Internet Security is configured to scan incoming and outgoing mail messages. The real time scanning of email messages for viruses is working but the spam scanning doesn’t work.

In the real time scanning window (mail protection) I can see the scanned/infected counter is increasing, but for antispam the counter is always zero.

In the mail.log file I see only this:

22.10.2011	14:31:15	000007D0:   SMTPs Start: 1
22.10.2011	14:31:15	000007D0:   SMTPs RedirectPort: 465
22.10.2011	14:31:15	000007D0:   IMAPs Start: 1
22.10.2011	14:31:15	000007D0:   IMAPs RedirectPort: 993
22.10.2011	14:31:15	000007D0:   NNTPs Start: 1
22.10.2011	14:31:15	000007D0:   NNTPs RedirectPort: 563
22.10.2011	14:38:48	000012D0:   --IMAP Mail is clean
22.10.2011	15:04:29	000001F8:   --SMTP Mail is clean

In the EmailShield.txt file I see informations about the incoming mail messages and the status.

Any hints, why spam scanning is not working? Thanks.

Install Mailwasher Free from: http://www.mailwasher.net/

It enables you to read emails straight off your ISP’s mail server without the need to download them to your own machine first. Most SPAM will be marked as such and you can simply delete it, but you can also build your own SPAM filters to delete any originating from the same source automatically so that you never even see it.

Is the following of any help?
https://support.avast.com/index.php?_m=knowledgebase&_a=viewarticle&kbarticleid=750#idt_16