Exchange Outlook Anywhere Authentication Issue

Have you been able to resolve this problem? If not, there may be a couple things you could try.

If you were to connect directly to the Exchange server, what username would you need to use? You could try using tcpdump to capture the traffic between client and F5 and F5 and backend server. I assume you'll be using HTTPS, so you would need to use ssldump to decrypt the packets as well. You may be able to see better the request/response with the backend server and determine where the issue is happening.