When you ost file damage then you can try convert OST to PST tool on off-line Exchange Server and simply export MS Outlook OST to PST file along with whole e-mail entities. It is 3rd party OST Repair tool use on down Exchange Server to simply retrieve Outlook e-mails from inaccessible OST file.
Outlook client use this tool on following satiation to simply retrieve MS Outlook emails, which is:
1. If your Exchange Server becomes down
2. When OST file is over-sized
3. When you are Update your Exchange Server due to corruption of hardware or software in Exchange Outlook Email Database
4. Virus Attack on Exchange Server and not resolve error though any anti-virus
Read more : http://www.osttopstconvert.recoveryfiles.org/
Or
http://www.osttopsttool.com/
