Advanced Exchange Recovery uses advanced technologies to scan the orphaned or damaged Exchange offline folder (.ost) files, recover your mail messages and other items as much as possible, & convert them into an Outlook pst data file for easy access.
Note: For Outlook PST file repair and recovery, please use Advanced Outlook Repair. - Solution for Following Common Errors and Problems in Exchange OST File - Cannot open your default email folders. The file xxxx.ost is not an offline folder file.
Unable to expand the folder. The set of folders could not be opened. Errors could have been detected in the file xxxx.ost.-Various errors when synchronizing Exchange Server mailbox with your OST file.