TABLE OF CONTENTS The Client Access Server (CAS) replaces the front-end server we all know from Exchange 2000 and 2003 and adds some additional functionality. The CAS provides mailbox access for all types of Exchange clients except Outlook MAPI clients, which, as most of you are aware, connect directly to the Mailbox Server on which the respective mailbox is stored. This means the CAS manages access for any user who opens their mailbox using Outlook Anywhere (formerly known as RPC over HTTP), Outlook Web Access (OWA), Exchange ActiveSync (EAS), POP3, and last but not least, IMAP4.
In addition to providing client access, the CAS is responsible for supplying access to things such as automatic profile configuration, free/busy information, Out of Office (OOF) messages, the Offline Address Book (OAB), as well as Unified Messaging (UM), but only for Outlook 2007 and Outlook Web Access 2007. Only these two client versions can take advantage of the new Web-based Exchange services known as the AutoDiscover and Availability services. Legacy clients such as Outlook 2003 and earlier cannot use these two new Exchange Web services.
After reading this chapter, you should have a good understanding of how you can manage the feature set on the CAS, at both the server level and organizationwide.
The Client Access Server should always be deployed on a domain-member server on the internal network, and not in the DMZ, which many thought was a security best practice for front-end servers in Exchange 2000 and...
