MAPI (Messaging Application Program Interface) is a Microsoft Windows program interface that enables you to send e-mail from within a Windows application and attach the document you are working on to the e-mail note. Applications that take advantage of MAPI include word processors, spreadsheets, and graphics applications. MAPI-compatible applications typically include a Send Mail or Send in the File pulldown menu of the application. Selecting one of these sends a request to a MAPI server.
MAPI consists of a standard set of C language functions that are stored in a program library known as a dynamic link library (DLL). Developers who are using Microsoft's Active Server Page (ASP) technology access the MAPI library by using Microsoft's Collaboration Data Objects (CDO). The CDO library comes with Microsoft's Internet Information Server (IIS). MAPI functions can be accessed by Visual Basic developers through a Basic-to-C translation layer.
Eudora, one of the most popular e-mail programs, includes a MAPI server. To activate the Eudora MAPI server, select Options from the Tools pulldown menu and then double-click on MAPI and specify whether MAPI should always be active or whether it should be active only when Eudora is running. Microsoft Exchange and possibly some other programs may require that you turn the MAPI server off when they are in use.