Accessing the public information store is similar to accessing any other MAPI message store. MAPI methods are used to perform most functions, but some parameters to these methods differ from the ones used by other MAPI functions. Most MAPI client applications do not distinguish between public and private folders; this is a Microsoft Exchange Server distinction.
Special wrapper functions facilitate access to the Microsoft Exchange Server public information store. These functions hide some MAPI programming details when public information store operations are performed.
For example, when used with the entry identifier of a message store, the HrOpenExchangePublicStore function allows you to open a public information store. The FIsPublicStore function enables you to determine whether an open store is public. Once you’ve obtained the interface object for the public information store, you can use the public folder functions of Microsoft Exchange Server to manipulate the public folder. For more information, see Determining the Type of Information Store.
Unlike the private information store, the public information store makes no distinction between folder types. It can, in fact, be considered a special type of mailbox that holds a group of public folders created by administrators, users, or applications.
Public folders can only be accessed by persons or applications with sufficient permissions. For more information, see About Information Store Security.