OL98: (IMO) Attributes of the Personal Folder in Outlook 98

This article discusses the purpose and capacity of the Personal Store storage facilities used by the Internet Mail Only installation of Microsoft Outlook 98.

A Personal Folder file, also known as a .pst, is the medium for storing Mail Application Program Interface (MAPI) objects created or received by Microsoft Outlook 98. Unlike a MS-DOS or Windows file system, the .pst is only accessible by a MAPI aware program such as Outlook.

One or more .pst files can reside on your computer. A .pst can be defined as your primary store, meaning that your mail is delivered to the Inbox in that file and all of your other default Outlook folders, such as Calendar, Contacts, Deleted Items, Journal, Notes, Sent Items, and Tasks reside there. Or, a .pst file can be defined as a secondary store, meaning you can move items to it, either manually or with Inbox Rules, from your primary store.

Each .pst file can contain as many folders as you want and each folder can contain a maximum of 16 Kilobytes (KB) records. The total file size of a .pst cannot exceed 2 Gigabytes (GB).

For more information about this subject, please see the following articles in the Microsoft Knowledge Base: