As expected, Microsoft wanted this version of Exchange to be the best product released to date. With the release of Exchange 2000, Microsoft had lost focus of what Exchange is supposed to bea messaging platform. The introduction of collaboration and presence features in Exchange 2000 subtracted from the core goal of providing the best messaging platform and instead made the product among the front-runners but not the best. Exchange 2003 changed that and got back to the goal of being a great messaging platform. Let's examine the features that are no longer included in Exchange 2003.
Chat, Instant Messaging, Conferencing
In Exchange 2003, Microsoft removed the Microsoft Exchange Chat service, which was available in the Exchange 2000 Enterprise Edition. Unlike instant messaging (IM), which is an ad hoc environment, Exchange chat implemented virtual chat rooms that supported one-on-one communications and multiparty chats. Although Exchange Chat can still be used in mixed environments with Exchange 2000 and Exchange 2003, the feature must be removed before upgrading the entire server environment to Exchange 2003.
Microsoft also removed the Exchange Instant Messaging feature from Exchange 2003. Microsoft faced several issues in this arena with client compatibility, communication security, and incompatibility with other IM platforms such as Yahoo, MSN, and AOL. The inability to combine users of different systemsfor example Exchange and Yahoointo one conversation was a big shortcoming in leveraging the availability of presence information.
Microsoft also removed the Exchange Conferencing Server (ECS) from the feature set of Exchange 2003. An add-in product that ran on top of Exchange 2000, ECS provided audio, video, and data conferencing as well as conference-scheduling management. Because there is no replacement product for ECS in Exchange 2003, you'll need to look at Microsoft Office Live Meeting for ECS-type features.
Microsoft has not left the arena in regard to its collaboration and presence products. It has continued its efforts to develop stable, reliable, and functional products to fulfill customer needs for real-time communications. Microsoft Live Communications Server 2005 (MCLS 2005) delivers instant messaging (IM) and presence as part of a scalable, enterprise-caliber solution. MCLS 2005 offers enhanced security, seamless integration with other Microsoft products, and a development platform that can be enhanced by programmers. The product functionality is based on the Session Initiation Protocol (SIP) and SIP for Instant Messaging and Presence Leveraging Extensions (SIMPLE), as well as the Real Time Protocol (RTP). Check out this product if you require real-time communications in your organization.
Officially known as the Exchange Installable File System (ExIFS) in Exchange 2000, on new Exchange 2000 installations and upgrades from Exchange 5.5, ExIFS was automatically assigned to the M: drive and mapped to the information store as a way to programmatically manipulate items in the information store. To prevent unintentional data-corruption issues that may occur as a result of manually modifying data on drive M, or as a result of file-level virus scanning or backup-and-restore operations on drive M, Microsoft discontinued the drive mapping in Exchange 2003. If this mapping is required for legacy applications or mission-critical applications, you can enable the M: (or any other drive letter) back into the \\.\BackOfficeStorage\ namespace via a Registry key setting. However, the recommendation is to leave this feature disabled.
MAPI, MAPI Common Message Calls
Although Exchange 2003 is still a solid platform for development for application programming interfaces (APIs), data access methods, and other coding objects, some of the development technologies have been removed. Exchange 2003 no longer supports the use of Common Message Calls (CMC), which offers the basic capability to send and receive messages from messaging-aware applications, or Simple MAPI (SMAPI), which contains 12 Windows-based programming calls. Both of these features are interfaces to the Messaging Application Programming Interface (MAPI) subsystem, the heart of Microsoft's messaging programs. Even though these features have been removed, programmers can still develop applications via the Extended MAPI, which serves as the programming interface for C++ developers.
As with the other deprecated features mentioned in the previous subsections, several mail connectors available in Exchange 2000 and earlier versions have been removed in Exchange 2003. These legacy connectors can exist in a mixed Exchange 2000/Exchange 2003 messaging environment, but must be removed prior to upgrading to Exchange 2003. The legacy connectors are as follows: