Exchange Server 2007 represents a complete re-envisioning of enterprise e-messaging for the Microsoft platform. Server roles play a central part. Use these guidelines to right-size server hardware and plan enterprise deployment.

One Actor, Five Roles

Exchange Server 2007 parses core messaging functions into five roles. Begin by understanding the roles and their functions.

• Client Access Server. This role answers all non-MAPI access requests such as those made via Outlook Web Access, Exchange ActiveSync, POP3, and IMAP. The Exchange ActiveSync Direct Push feature automatically synchronizes data to mobile devices (forwarding e-mail, for example), but will only work with cellular devices, not over Wi-Fi. When implemented in a redundant architecture, the Client Access Server role can also perform load-balancing.
  • Do not confuse this role with the front-end server for Exchange 2003. The Client Access Server off-loads significant processing tasks from the Mailbox Server including Exchange ActiveSync policies...