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.OST File Extension

File TypeOutlook Offline Folder File

3.0 (21 Votes)
CategoryMisc Files


This file is saved in a binary format, which requires a specific program to read its contents.

What is an OST file?

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.

More Information

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.

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Programs that open OST files
Updated 4/10/2017

About OST Files

Our goal is to help you understand what a file with a *.ost suffix is and how to open it.

The Outlook Offline Folder file type, file format description, and Windows programs listed on this page have been individually researched and verified by the FileInfo team. We strive for 100% accuracy and only publish information about file formats that we have tested and validated.

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