This article was previously published under Q181406
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NOTE: These procedures only apply if you have installed Outlook with the Corporate Workgroup/Other option. This option allows you to use Messaging Application Programming Interface (MAPI) services. To determine your installation type, on the Help Menu click About Microsoft Outlook. InAbout Microsoft Outlook you should see "Corporate" if you have theCorporate or Workgroup installation.
This article discusses the purpose and capacity of each of the followingstorage facilities used by Microsoft Outlook 98 when running as a client toa Microsoft Exchange Server:
Personal Folders (.pst) files located on the user's computer.
Offline Store (.ost) files located on the user's computer.
Mailbox Folders located on the Microsoft Exchange Server.
Public Folders (PF) located on the Microsoft Exchange Server.
Personal Folders Files Located on Your Computer
One or more .pst files can reside on each user's computer. A .pst can be defined as your primary store or as a secondary store. A primary store means that mail 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. A .pst file can also be defined as a secondary store, which means you can move items to that file, either manually or with Inbox Rules, from your primary store.
Each .pst file can contain 16,384 items. An item is either a folder, message, task, etc. Each folder can contain a maximum of 16,384 items. If you select the option to "Allow upgrade to large tables," each folder can contain up to 65,536 items. The total file size of a .pst cannot exceed 2 Gigabytes (GB).
Offline Store Files Located on Your Computer
Only one .ost file can reside on each user's computer. The .ost is alwaysdefined as your primary store, meaning that your mail is delivered to theInbox in that file and all of your other default Outlook folders, such asCalendar, Contacts, Deleted Items, Journal, Notes, Sent Items, and Tasksreside there. The .ost differs from the .pst in that items residing in itcan also reside in the Mailbox on the server. You can synchronize the .ostand Mailbox folders so that they always contain the same information. Thisallows you to work offline when the server is unavailable; then whenreconnected to the server, changes made offline will be uploaded to theserver and then mail received while offline downloads to the .ost.
The .ost file can contain as many root folders as you desire and eachfolder can contain a maximum of 16 KB subfolders. If you select the optionto "Allow upgrade to large tables," each folder cancontain up to 64 KB subfolders. The total file size of an .ost cannotexceed 2 GB.
Mailbox Folders Located on the Microsoft Exchange Server
A Mailbox Folder for each user is stored on the server in the samedatabase store. The server has a capacity of 16 GB for one store, howeverthe server administrator may limit the size of each user's Mailbox Folder.
Note: this limitation does not apply to the Enterprise edition ofMicrosoft Exchange Server version 5.5. Store sizes are restricted to drivespace installed and available on the server. If larger capacity drives areinstalled on the server, the stores can grow to the size available. Thisis not true of the Standard edition of Microsoft Exchange Server, whichhas the same store size limits as previous versions.
Public Folders Located on the Microsoft Exchange Server
Public Folders (PF) reside on the server in the same database store. Theycontain information shared by many users. Depending upon accesspermissions, individual users can read, update, or add to the Public Folder. The server has a capacity of 16 GB for one store.
For more information about this subject, please see the following articlesin the Microsoft Knowledge Base:
182158OL98: (CW) What Are Offline Folders and How Do You Use Them?