MAPI

Messaging Application Programming Interface (MAPI) is a messaging architecture and a Component Object Model based API for Microsoft Windows. MAPI allows client programs to become (e-mail) messaging-enabled, -aware, or -based by calling MAPI subsystem routines that interface with certain messaging servers. While MAPI is designed to be independent of the protocol, it is usually used with MAPI/RPC, the that Microsoft Outlook uses to communicate with Microsoft Exchange.

MAPI uses functions loosely based on the X.400 XAPIA standard. It includes facilities to access message transports, message stores, and directories.

While Simple MAPI (SMAPI) is a subset of 12 functions which enable developers to add basic messaging functionality, Extended MAPI (EMAPI) allows complete control over the messaging system on the client computer. This includes creation and management of messages, plus management of the client mailbox, and service providers.

Simple MAPI ships with Microsoft Windows as part of Outlook Express/Windows Mail while the full Extended MAPI ships with Office Outlook and Exchange.

In addition to the Extended MAPI client interface, programming calls can be made indirectly through the Simple MAPI API client interface, through the Common Messaging Calls (CMC) API client interface, or by the object-based CDO Library interface. These three methods are easier to use and designed for less complex messaging-enabled and -aware applications. (Simple MAPI and CMC were removed from Exchange 2003.)

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