The best tool to convert OST to PST OST files are used by Outlook mainly in the MS exchange server . The data stored within OST files get synchronized with the PST files and with the online server, when the connection to the server is present. OST files allow users to access their emails, contacts, tasks, calendar entries, and other items offline. However, there could be many instances when OST file gets corrupt, and you can’t access any of your items. In an office environment, this could get even more frustrating and users could easily go into panic mode. The causes for OST file corruption could be many. Some of them include: Crashing of the exchange server Server down due to maintenance Hardware failures Virus, malware attack Power failure Accidental loss of the original exchange account Scanost.exe is an inbuilt tool in Windows that scans OST file for any issues, and if found any, repairs it. But, Scanost.exe is an incomplete tool, which fails many times, and do