OST File Extension

What is OST?

OST stands for Offline Storage Table. The file extension allows MS Outlook users to work offline and connects automatically with Exchange Server as the server connection comes back. OST file format was introduced in the MS Outlook family in 2005 or later. Like PST, it stores emails, notes, messages, contacts, events and many other databases of MS Outlook. OST is a widely used file format for MS Outlook because of its ability to allow users to work offline.

More about OST File Format

OST files store in the local system. Users can access their important emails, notes or messages anytime regardless of the slow or poor internet connection. Users can independently work offline. They can create email, contacts and appointments. They search or add contacts. Any changes made in offline mode are synchronized with the user account when the server connection comes back. Users create an offline folder when they select 'Use Offline Folders' option in Outlook. The file location is -

If you want to locate the file location manually, go to Filethen Account Settings, choose the Data Files tab, clicking an entry and then choose 'Open Folder Location'.

It is important to understand that there is no difference between OST and PST. The only difference is their file location. OST saves data offline where PST works online.

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• MS Outlook 2003, 2007, 2010, 2013, 2016