I am doing an upgrade for a network that has 8 branch offices. Four of those offices have Exchange 2003 servers currently; all mail flows into one server and then is routed to the appropriate mailbox. We are upgrading to Exchange 2010 and I was wondering if anyone had suggestions for the topology to implement. From what I have been reading it looks like at each of the four locations I will want to install the CAS, Hub Transport, and Mailbox role. My question is since what would be the best way to set this up so I only have to purchase one SSL cert for OWA. Should I set up a proxy for the CAS? Since each location will have mailboxes I am assuming the proxy would then route them to their mailbox. Is the rest done via connectors as far as email flow - the emails will come into one location and then be dispersed. Is there a best practice way to do this? Any suggestions would be grealty appreciated. Thanks.