Answer

Alwil Avast! for Kerio works with Kerio MailServer on Windows NT/2000/XP/2003.

To install:

1. Download avast! for Kerio.
2. Install avast! for Kerio. If you have any trouble with the installation, you can contact Alwil for free technical support.
3. Open the Kerio Administration Console and connect to Kerio MailServer.
4. Go to Configuration->Antivirus.
5. Click on "Select antivirus..." (near the top).
6. Choose "Alwil avast! 4.0 for Kerio"
7. Click "Check & OK." After a second, you should get a message saying "Antivirus started."

avast! should now be working properly and scanning your incoming and outgoing email!!