MAPI – This is the messaging API (``Application Programming Interface'') for Microsoft Windows platforms. MAPI exposes functions that allow programmers to interface to a messaging architecture across a variety of 16 and 32 bit Microsoft Windows platforms with little or no change to the code required to access the functionality.

The messaging architecture that is accessed allows automated clients, and computer users to control and access shared applications such as email, scheduling, calendaring, document management, and faxes through network and user interfaces.

MAPI has been included with Microsoft Windows since Windows95/NT and can be downloaded from Microsoft for other Windows systems for free.