MAPI Features and Architecture
Messaging API (MAPI) is composed of a set of common application programming interfaces and a dynamic-link library (DLL) component. The interfaces are used to create and access diverse messaging applications and messaging systems, offering a uniform environment for development and use, and providing true independence for both. The DLL contains the MAPI subsystem, which manages the interaction between front-end messaging applications and back-end messaging systems and provides a common user interface for frequent tasks. The MAPI subsystem acts as a central clearinghouse to unify the various messaging systems and shield clients from their differences.