Understanding Public Folders and System Folders

Each public folder tree contains two subtrees:

• Public folders (also known as the IPM_Subtree)   Users can access these folders directly with client applications like Outlook. In its default configuration, Exchange System Manager displays these folders when you expand a public folder tree.

• System folders (also known as the Non IPM_Subtree)   Users cannot access these folders directly. Client applications like Outlook use these folders to store information such as free and busy data, offline address lists, and organizational forms. Other system folders hold configuration information that is used by custom applications or by Exchange itself. The Public Folders tree contains extra system folders, such as the EFORMS REGISTRY folder, that do not exist in general-purpose public folder trees.

By default, Exchange System Manager displays public folders instead of system folders.

The Folders node in Exchange System Manager

Under normal operating conditions, you do not have to interact with system folders frequently. In Exchange System Manager, you can view the system folders for a specific public folder tree by right-clicking the public folder tree node and clicking View System folders.

Folders node in Exchange System Manager that displays the system folders

System folders include the following:

• EFORMS REGISTRY and Events Root   By default, one content replica of each of these folders resides in the default public folder store on the first Exchange 2003 or Exchange 2000 server that is installed in the first administrative group.

• Site folders (OFFLINE ADDRESS BOOK and SCHEDULE+ FREE BUSY)   In most respects, these folders function in the same manner as other public folders, with the following additions:

  • Site folders exist only in the Public Folders tree.

  • The OFFLINE ADDRESS BOOK folder and the SCHEDULE+ FREE BUSY folder automatically contain a subfolder for each administrative group (or site) in your topology. By default, a content replica of a specific administrative group folder resides on the first server that is installed in the administrative group.

  • Each administrative group has a Site Folder Server, identified in the administrative group's object in Active Directory. By default, the first server in the site is a Site Folder Server. This server is responsible for making sure that site folders exist. If you have to remove the Site Folder Server from the site, first make sure that the site folders have been replicated to a new server that can take over as the Site Folder Server.

• OWAScratchPad folders   Each public folder store has an OWAScratchPad folder, which is used to temporarily store attachments that are being accessed with Outlook Web Access. Do not modify these folders.

• StoreEvents folders   Each public folder store has a StoreEvents folder, which holds registration information for custom store events. Do not modify these folders.

• Other folders   To support internal store operations, a tree may contain several other system folders. Do not modify these folders.