Public folders are distinguished from private foldersby several characteristics:
They are accessible by people or applications throughout the organization, provided those people or applications have the necessary permissions to access the folders. For more information, see About Information Store Security.
They are location-independent within a site.
They support replication between servers in a site and between sites in an organization. The fact that they are replicated means replication conflicts can occur in their content.
They support public folder affinity, which is the ability of a client application to look at a server on another site and access a public folder. As an alternative to replicating that folder to the local site, public folder affinity is normally used if a high-bandwidth connection exists.
To develop applications that use public folders, you use MAPI interfaces. These interfaces enable you to directly manipulate public folders, their properties, and their contents in the information store. Microsoft Exchange Server functions that may also be used with public folders include FIsPublicStore, HrFindExchangePublicStore, and HrOpenExchangePublicStore.
For more information about using MAPI to program folders, see the MAPI Programmer's Reference. For information about folder objects, see Folder Object.