Testing has shown us that we must disable SSL on the "Microsoft-Server-ActiveSync" VD on Exchange 2003 server, as well as enable integrated auth on that VD. Or the users with mailboxes on 2003 and CAS ...
None that I am aware of, I don't really see a point though, only enable activesync for the users who need it, and have some kind of password lockout policy that will stop a device from trying to guess ...