I am using Outlook 2010 and have the same issue around the AntiSpam plug-in and have had the following message from Avast Technical Support:
Hello,
I am sorry but at this moment we do not plan to create new AntiSpam toolbar for Outlook.
Best regards,
Jakub Vanous
AVAST Software a.s.
Which would indicate the Avast is not going to support the automatic removal of Spam mail any longer. Looks like I for one (after 4-5 years of happily using the product) will be looking for a new Internet Antivirus/Firewall, etc. suite!
Hope this helps clear things up for users wondering what is going on!