File Type Outlook Offline Data File IconOutlook Offline Data File
File Format Proprietary (Microsoft)
Usage Open manually; may be referenced by an application
Rank ★ ★ ☆  Average

Stores e-mail messages and other data saved by Microsoft Outlook (2005 or later) from an Exchange server; similar to a Personal Folder (.PST) File, but supports larger file sizes.

OST files are created when the "Use Offline Folders" option is selected in Outlook and are stored on the local hard drive instead of mail server.

Open With

IconMicrosoft Outlook

IconRemo Convert OST to PST

IconOEMailRecovery.com Outlook Recovery Toolbox

Updated January 30, 2018