A MAPI client application is any application that uses one of the three MAPI client interfaces (Simple MAPI, CMC, and the Active Messaging Library) or the MAPI programming interface. Client applications implement messaging tasks as either their primary or secondary focus. Messaging client applications, such as applications that send and receive electronic mail, implement messaging as their primary focus while for non-messaging client applications, such as inventory or configuration applications, it is a secondary feature.
Client applications can be organized into one of the following three categories:
A messaging-aware application does not require the services of a messaging system, but includes messaging options as an additional feature. For example, a word processing application that includes a Send command in its File menu to allow documents to be sent is considered messaging-aware.
A messaging-enabled application requires the services of a messaging system and typically runs on a network or an online service. An example of a messaging-enabled application is Microsoft Mail.
A more advanced client application is the messaging-based workgroup application. The workgroup application requires full access to a wide range of messaging system services, including storage, addressing, and transport services. These applications are designed to operate over a network without users having to manage the applications' network interaction. Examples of such applications include work flow automation programs and bulletin board services.
Client applications can either include the user to create an interactive environment or operate without a user in an automated environment. While MAPI supplies a set of common dialog boxes with its standard user interface, client applications are not required to present a user interface. In fact, all processing can be handled within the application if desired. An example of an automated client application would be an inventory management application that is programmed to route items of a particular type to standard recipients on a regular basis.