Which file extension is associated with Outlook data storage?

• A. .pst
• B. .ost
• C. .pstx
• D. .mbox

Answer: (A)

Outlook stores mailbox data in a local file called a Personal Storage Table, identified by the .pst extension. This file holds emails, contacts, calendar items, tasks, and other mailbox data in one portable container, and it’s the standard storage format used for POP accounts and for exporting or moving data. The .ost file is also used by Outlook, but it serves as an offline copy of an Exchange/Office 365 mailbox rather than the primary storage container. The other extensions shown aren’t typical Outlook data storage formats—.mbox is associated with other mail clients, and .pstx is not the standard Outlook data file. So the extension most closely associated with Outlook data storage is .pst.