I battled this for the last 2 weeks and was getting nowhere until today. I have a similar setup - Exchange 2007 Internet facing CAS servers which proxy to internal CAS servers. The internal CAS servers were fine, buttons and icons all visible and working. On the external facing ones, message icons were there, but no buttons, then eventually the icons were missing as well. After uninstalling / reinstalling the extensions countless times, I removed and reinstalled the "owa" virtual directory on the external facing CAS server - fixed everything. Make sure your internal CAS owa and exchange virtual directories are configured for integrated windows authentication. Symantec tried to get me to go through the whole contrained delegate process, etc., etc. I can't very well remotely upgrade Windows 2000 servers all around the country just to get OWA to work. So in the end, my problem was a hosed up OWA virtual directory. Also, I'm running Exchange 2007 on Windows 2008, which is not "officially" supported by Symantec yet. I suspect it may be becuase of the differences in IIS, but I was unable to get an answer on that as well. Not supported and not certified are different in my opinion. If you go the route of reinstalling the OWA virtual directory, here is a good resource:
http://exchangeshare.wordpress.com/2008/07/16/how-to-recreate-owa-virtual-directory-exchange-2007/
Make sure you have logging enabled in your web.config file though, it may shed more light on your particular situation.
Hope this helps.
Message Edited by jgrant50 on 09-10-2008 11:03 AM
Message Edited by jgrant50 on 09-10-2008 11:04 AM
