Lesson 1: Microsoft Messaging API (MAPI) | Microsoft Windows Architecture for Developers Training Kit

MAPI Architecture

With the MAPI subsystem, you can easily add messaging features to any Windows-based application. This makes basic workgroup activities such as information sharing easy for end users. MAPI also gives organizations the freedom to choose messaging systems and applications that best meet their needs, rather than choosing from the few that might be compatible. And because MAPI is part of the Windows operating system, all messaging systems and applications can be integrated on a user 's desktop with familiar graphical tools. This lesson explains the benefits of MAPI and how it works.

MAPI includes all the functions and object-oriented interfaces that form the foundation for the MAPI subsystem's client application and service provider interfaces.

You can use MAPI to create mail-enabled applications. MAPI's core system components allow you to connect any mail-enabled or workgroup application seamlessly to MAPI-compliant information services. For example, the Microsoft Exchange messaging system can be connected to most private or public e-mail systems through the use of MAPI drivers.

The MAPI front-end, or client, APIs are available in three parts . Simple MAPI and the Common Messaging Calls (CMC) support those applications that require only basic messaging functions. Extended MAPI is used for creating advanced messaging-based applications.

Simple MAPI

Simple MAPI includes the most common functions for you to make applications mail-aware. Examples of mail-aware applications include spreadsheet programs and word processors. Simple MAPI can also be used to build custom messaging applications. Although Simple MAPI has limited functionality and can be used only in the Windows environment, it provides the ability to:

Log on and off a messaging system.
Find and read messages.
Address new messages by adding recipients.
Add attachments to messages.
Save and send messages.

Common Message Calls

Just as with Simple MAPI, CMC contains functions for you to make applications mail-aware. It also can be used to create custom messaging applications. CMC was designed to minimize the number of function calls needed to send or receive a message. For example, a mail-enabled application can send a message with a single function call and receive a specific message with two calls. Unlike Simple MAPI, CMC:

Is independent of the operating system and hardware used by the messaging service.
Supports multiple network platforms.
Allows you to use multiple messaging services.

Note
The Simple MAPI and Common Messaging Call SDKs are available on the Microsoft Developer Network (MSDN).

Extended MAPI

Extended MAPI is a more complex, object-oriented API that is intended for applications that need to make frequent, heavy use of a mail system. Extended MAPI provides the following messaging capabilities:

Management of a large number of received messages.
Management of complex message and addressing information.
Unattended message filtering.
Support for advanced message features such as custom forms and smart forms.

With custom forms, an organization can replace a standard send and receive mail form with a custom timesheet or calendar form. In addition, the custom form can have its own predefined information fields.

Smart forms are similar to custom forms, but they can link information from fields on a form to other applications. For example, timesheet information can be obtained automatically from the message system and sent to a host application such as a payroll program.