How to restore your Outlook mailbox on Exchange Server in the event of OST corruption?
OST file is created by MS Exchange Server in a local Windows Server. It is created in the same drive location of your Outlook PST files. When link between MS Outlook and Exchange mail server could not be established due to various reasons, Outlook mailboxes of mail server are saved in Offline folders or OST files. Each OST file contains a single Outlook user mailbox and allows a user to access emails in offline mode.