Thanks for you reply Dayne. We did configure the CAS array, pointing it to the FQDN of the LTM's RPC VS. We also mapped the Mailbox DB to use the LTM's RPC VS via the FQDN. It does seem to pick that up as when I try to configure a new Outlook profile, if I type the real server name (one of the pool members FQDN) and a user account, it finds the user and changes the server name to be the FQDN of the VS. However, it will not connect using the FQDN that points to the RPC VS.
What puzzles me is the fact that on the tcpdump DCERPC reject packet, the server replies to the client with its own FQDN and IP address. I am not too sure if this is the normal Exchange behaviour after having created the CAS array and CAS FQDN.
Nimbostratus