As noted in a previous article I was tasked by a client with figuring out why their Retrospect Backup software for Windows was not working properly. Since I was not familiar with Retrospect I had to troubleshoot from the beginning. I started troubleshooting on the Windows 2003 R2 server running Retrospect and was able to easily see the log files showing the errors backing up one of the companies Exchange servers. When I attempted to manually backup a single mailbox on the Microsoft Exchange server I was receiving the same errors. Below I describe the Retrospect backup error and then explain step by step how I was able to resolve the error.