pst

In computing, a Personal Storage Table (.pst) is an open proprietary file format used to store copies of messages, calendar events, and other items within Microsoft software such as Microsoft Exchange Client, Windows Messaging, and Microsoft Outlook. The open format is controlled by Microsoft who provide free specifications and free irrevocable technology licensing.
The file format may also be known as a Personal Folders (File) or Post Office File. When functioning in its capacity as a cache for Outlook's Cached Exchange Mode feature, it may be called an Off-line Storage Table (.ost) or an Off-line Folders (File).

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