Opening OST files

Did your computer fail to open an OST file? We explain what OST files are and recommend software that we know can open or convert your OST files.

What is an OST file?

Files that contain the .ost file extension are used by the Microsoft Outlook email application. The OST files store email messages that have been saved from an exchange server by the Microsoft Outlook application.

The OST files that are used by Outlook are created when a user chooses the "Use Offline Folders" option in the Outlook application. When this option is selected, the application stores the folders on the local hard drive instead of on the actual mail server that the application would usually download the files from. These files are then saved with the .ost file suffix.

OST files are similar in nature to PST files, but OST files allow for larger file sizes.

Try a universal file viewer

In addition to the products listed above, I would suggest that you try a universal file viewer like Free File Viewer. It can open over 200 different types of files - and very likely yours too! Download Free File Viewer.

By Prof. Jones (The File Expert)

Chief Content Editor and File Expert

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