Before you can communicate with service providers and an underlying messaging system, you must establish a session. A MAPI session is a link from a client to other MAPI components. As the result of successfully starting a session, MAPI returns to clients a pointer to a session object — an object that implements the IMAPISession interface. You can use the methods of the IMAPISession interface to access the objects of address book and message store providers, access several tables, display forms, set transport provider properties, and perform profile and message service administration.