Server components providing services for Microsoft Exchange Server often reside on a dedicated computer. The significant components of a server running Microsoft Exchange Server are the directory, information store, and gateways. The following diagram represents the interaction among these components.
Server applications developed for Microsoft Exchange Server interact with components such as the information store and the directory, similarly to the server service for Microsoft Exchange Server, and offer custom services to clients. Server applications can function independently of clients, or they can include a client component. Also, server applications, like client applications, communicate with Microsoft Exchange Server through MAPI.