Exchange supports multiple public folder hierarchies and each hierarchy (or tree) is stored in a public folder store. The default server installation includes one public folder store that contains one public folder hierarchy. Only one public folder hierarchy can be stored in a public folder store.
A public folder store cannot be created without first creating a public folder hierarchy to store in it. If you try to create a public folder store without an available public folder hierarchy, the following error message appears:
All the public folder trees already have an
associated public store on the server. You need
to create a new public folder tree before creating
this new public folder store.
The default public folder store contains the All Public Folders hierarchy. This store must be associated with every mailbox store on a server to ensure that the All Public Folders hierarchy is displayed in IMAP and MAPI mail clients. Any additional hierarchies that you create are accessible from standard Windows applications in which the folders in the hierarchies are mapped as network drives using IFS, WebDAV, and NNTP clients. Use the extra hierarchies as file repositories for departments, groups, or projects.
The following table describes which hierarchies are visible to which clients:
| Client | Hierarchy |
|---|---|
| POP | None |
| IMAP | All Public Folders |
| MAPI | All Public Folders |
| NNTP | Internet Newsgroups |
| WebDAV browsers | All Public Folders and other mailboxes and folders accessed by WebDAV |
| Windows applications | Other mailboxes and folders shared with IFS |