I'm using the Zimbra appliance from rPath.
Fully configured and easy to install and use. I'm using an external LDAP replica for authtication and GAL with command line shell scripts to create the system.
So I'd guess you'd say I'm using a system "blessed" by Zimbra as confirmed working.
Have you checked out the thread:
http://www.zimbra.com/forums/adminis...e-clamav.html? It may help but it's germain to my set-up (or at least not yet).