I'm going to be migrating to Exchange 2007 and I just have a question about the Client Access server role. In the Exchange 2007 FAQ's, it states that you need to install the Client Access server roll in every AD site that contains a user mailbox. My network contains 10 sites(one for each subnet) and at each site there is a DC which is also a GC. I have 1 Exchange 2003 box. My question is, with this setup, do I need to install the Client Access server roll in the 10 sites I have or only in the site that my Exchange server will be since this server will also have the mailbox roll? Thanks in advance. Mike

Yes, Minimum one CAS server is requires only in AD sites where Exchange 2007 Mailbox Server role is installed so CAS can handle non-MAPI client requests for users whose mailbox is on Exchange 2007 Mailbox server. Understanding Exchange Server 2007 server roles

If you have one mailbox role you only need one CAS role, but it has to be in the same AD site

Hi Mike, You only need to install and at least install one Client Access server role in the site which contains user mailboxes, and as it reduces the use of corporate bandwidth by redirecting the connection to the Client Access server that is in the same Active Directory site in which the user's mailbox is contained. It is by design. For more information: Planning for Client Access Servers http://technet.microsoft.com/en-us/library/bb123811(EXCHG.80).aspx Hope it helps. Thanks, Elvis