Microsoft® Exchange Server 2007: Implementation and Administration

Chapter 15. Client Access Server Functions

While most of the components in Exchange Server 2007 have undergone considerable change, few components have been as dramatically overhauled as the Exchange Server 2003 front-end server. The front-end server role has been replaced by the Client Access server role which is no longer optional.

The Client Access server role is involved in almost all methods of Exchange 2007 mailbox access, including Outlook Web Access (OWA), IMAP/POP3, Exchange Active Sync, and Outlook Anywhere (formerly RPC over HTTP). The only access method in which it isn't directly involved is the standard Exchange MAPI over RPC connection. As you will see, even for this method of connection, the Client Access server is still involved with the provisioning of offline address books and Free/Busy information.

The Exchange 2007 Client Access server implements new ways to access the offline address book and access Free/Busy information. These services are only available from Outlook 2007 and Outlook Web Access 2007 clients. Legacy clients such as Outlook 2003 make use of the public folder access methods used in Exchange 2003. The Client Access server also provides functionality for Unified Messaging by enabling the pin reset and play-on-phone features, and it is also where Exchange Web Services are provided. The Exchange Web Services form the basis of the Autodis-cover feature used by Outlook 2007 to automatically configure Outlook profiles and will become the standard method ...