Perhaps the most significant change between Exchange 2007 and Exchange 2010 is the move to channel Outlook connectivity through the CAS role.  In Exchange 2007 Outlook would connect to the mailbox role, whilst other protocols (POP, OWA, IMAP etc.) would leverage the CAS role. 


In Exchange 2010 this means that we now find two new services installed on the CAS role:

  • RPC Client Access
  • Address Book service

These services are responsible for handling the Mail, NSPI and RFR client access connections from Outlook.  The mail RPC end point is still present in the Information Store but accepts connections only from CAS.  Public folder access is direct to the mailbox role, but Outlook connects to the RPC Client Access service on the mailbox role and not directly to the Information Store. 

Note that the RPC Client Access Service is also found on the Mailbox role as well, as explained above.


For a full listing of the services installed by Exchange 2010 setup please see:

Overview of Services Installed by Exchange Setup



References for RPC Client Access:

Understanding RPC Client Access

Understanding the Address Book Service

Exploring Exchange 2010 RPC Client Access service