If Cisco Unity loses connectivity with an off-box Exchange server, messages received during this outage are stored in the UnityMTA folder or directory. If connectivity is restored for a time interval of 10-30 seconds and lost again, Unity becomes stuck in Cisco Unity Message Repository (UMR) mode. Subscribers receive messages but cannot retrieve them. Some errors are logged in the Application Event viewer.
For more information on this error message, refer to Cisco bug ID CSCed51091.
For a workaround, restart AvUMRSyncSvr to restore normal functionality to Cisco Unity.
To avoid this problem in the future, you can apply Cisco Unity 4.0.3 Service Release 1 or later on your system.