Out BES (5.0.2) is having issues activating a single user, and RIM said that can't help anymore
I can activate other users without any issues just this user, when you look through the user information on the BES under the 'Component Information' tab the reported 'Messaging Server' is the server and not the CAS arrary as it does for all other users.
The user has been removed from the BES and re-added, and the user mailbox has been moved from one Exchange database to another.
When you attempt to active the device the ETP message is received in the users mailbox ok.
Any help or ideas of what else to check would be great, thanks in advance.