Our company is considering installing an Exchange Server. We are currently happy with our Server 2003.
The Exchange server will be Server 2008 R2 with Exchange 2010. My question is whether I have to upgrade all of the existing Server 2003 CALs to Server 2008 or if I will only need Exchange 2010 CALs. The 2003 portion of the network will not be changing and the 2008 server will only be used for Exchange and web service.