Windows Messaging Subsystem Components

Because e-mail and other messaging-enabled applications are becoming so ubiquitous, Windows 95 operating system includes a set of operating system–level components that provide built-in messaging services to any application that wishes to take advantage of them. The term Windows Messaging Subsystem is sometimes used to describe the set of messaging components that provide operating system–level messaging services to applications — much like a Printing Subsystem provides printing services to applications.

Windows 95 ships with a number of components which together make up the Windows Messaging Subsystem:

Microsoft Exchange Client. The built-in "Universal Inbox" in Windows 95, which is used to send, receive, and organize e-mail, faxes, and other information. It includes an OLE-compatible rich text editor used for composing and reading messages, as well as powerful custom views, searching, and filtering. Through the use of MAPI drivers (described below), the Microsoft Exchange client-server messaging and groupware client can work directly against most public or private e-mail systems.

MAPI. The core system components that seamlessly connect the Microsoft Exchange client and other applications to the various information services. MAPI's namesake component is the messaging application programming interface—the set of services that any mail-enabled or workgroup application can make use of. MAPI also defines a service provider interface (SPI) that allows MAPI drivers to be written for nearly any messaging and workgroup service. Sometimes called MAPI 1.0 to distinguish it from Simple MAPI interfaces found in earlier products.

Personal Address Book. The Personal Address Book (PAB) contains not only e-mail addresses, but names, phone/fax numbers, mailing addresses, and other personal contact information. Through the open MAPI interfaces, it is accessible from a wide variety of applications. The Personal Address Book can store addresses for multiple e-mail systems at the same time. The PAB is an example of a MAPI Address Book driver.

Personal Information Store. A sophisticated local "database" file that allows users to store e-mail messages, faxes, forms, documents, and other information in a common place. This provides the user with a set of Personal Folders that typically function as the user's Mailbox—including a universal inbox and outbox, as well as any other mail or document folders the user wishes to create. It supports long filenames, plus sorting and filtering on various fields of the stored objects. Custom views can be created and saved in the Personal Information Store. The Personal Information Store is an example of a MAPI Store driver.

Microsoft Mail drivers. A set of MAPI drivers that allow the Microsoft Exchange client to be used with a Microsoft Mail Postoffice, either the "workgroup edition" that's provided with Windows 95, or the "full" server edition that's available separately. Provides both LAN and remote functionality.

Microsoft fax drivers. MAPI drivers that allow the Microsoft Exchange client to send and receive electronic faxes just like any other piece of e-mail.

Internet mail drivers. Set of MAPI drivers that let the Microsoft Exchange client send and receive mail directly on the Internet, using the built-in TCP/IP and PPP communication protocols provided with Windows 95. Works either over a LAN connection or via dial-up.

CompuServe mail drivers. Set of MAPI drivers that let the Microsoft Exchange client send and receive mail via the CompuServe Information Service. Primarily used via dial-up.

(Optional) Third-party MAPI drivers. Drivers for other messaging systems will be available separately for more than 50 different messaging systems. The following are examples of messaging systems for which MAPI drivers are currently under development. You should contact these companies for more information about their drivers.