Where Does Outlook Store Emails? Most of your Outlook data is stored in what is called a PST file. If you are connected to a Microsoft Exchange server, your data will be stored in an OST file. PST stands for Personal Storage Table, OST for Offline Storage Table. You may be wondering where this PST file is actually stored in Outlook, and what exactly is saved on this file. Outlook saves all data onto the PST or OST file, including emails, contacts, calendars, tasks, notes and plenty of other items.