Most Microsoft Exchange Server interfaces are available through the MAPI extensibility mechanism for objects. To access an object with an interface other than a standard MAPI interface, you typically call the MAPI IMAPIProp::OpenProperty method and pass the appropriate property.
For example, you can obtain a stream interface on a message property such as PR_BODY. Call OpenProperty and specify the MAPI PR_BODY property and the Win32 IStream interface.
The Microsoft Exchange Server SDK contains the following functions that obtain a pointer to an interface:
For additional information on getting a pointer to an interface, see Obtaining Microsoft Exchange Server Interfaces.