One of the major changes in 2013 is the new architecture. Exchange 2013 only has two server roles:
- Client Access Server role;
- Mailbox Server role;
The other server roles that were available in Exchange 2007 and Exchange 2010 still exist, but are now known as Services. The Client Access Server (CAS15) consists of the Client Access Front-End (café) and the Front-End Transport (FET). The Mailbox Server role consists of the Mailbox Service, Unified Messaging Service, Client Access service (ambiguous naming I’m afraid) and the Hub Transport Services. The only exception is the Edge Transport Server role. When Exchange 2013 goes to RTM there won’t be an Edge Transport Server, this will be released with SP1 of Exchange 2013.