for what its worth, check our permissions which the BES service account has on the user account objects. The Service Account requires elevated access to pull in, act on and process the activation on a user account and mailbox object.
In exchange system manager Exc2003, delegation:
Blackberry Service account needs delegated to Exchange View only in Exchange 2003 (send as, receive as and administer information store)
Blackberry Service account needs Send As rights on User Objects in Active Directory at the container where the objects exist.
Remove the user from the blackberry server, verify it has cleared and add the user back, set the Wireless EA password and try activation from the device again. It should send the ETP message to the inbox, process it and start activation.
See link below for Installation for BES Exchange 4.14 Livelink - Redirection