Microsoft Exchange server is a client-server application which has been developed by Microsoft. This is mainly used by enterprises because it provides well sophisticated feature to use email, calendar, tasks etc services with strict authentication within the enterprise or organization. Therefore, it is being widely used by the big organizations for transfer of electronic mails etc. It stores emails in .ost file just like Microsoft Outlook stores emails and other stuffs in .pst file. The .ost file also gets corrupted due to several reasons like virus infection, exceed of size, misuse of file etc. Once the file gets corrupted, it degrades the working performance and gradually it stops working and whatever you make request to access your emails, you won't be able to access. In this case, you need to repair the .ost file using exchange .ost recovery software.
See also: Exchange ost recovery, .ost recovery, .ost file recovery, exchange .ost file recovery