This article refers to the Barracuda Backup Legacy Release firmware or newer, and Microsoft Exchange Server 2010.
If you encounter the error message "Error listing messages in a folder" or the message "Error opening message" when running message-level backups:
This error is due to backup threads established to your Exchange Server that are timing out. To resolve this issue, apply Service Pack 3 (SP3) to Exchange Server 2010, available from the Microsoft download center: http://www.microsoft.com/en-us/download/details.aspx?id=36768