I have a simple Win2003 SBS / Exchange 2003 environment consisting of one server. I now have a new one for Ex2010. How far can I deploy Ex2010 CAS without disturbing message flow to old Ex2003? If I don't modify DNS or firewall settings, can I complete the Ex2010 installation and have Ex2010 running while waiting for the weekend when I change the message flow to new server?

I have a simple Win2003 SBS / Exchange 2003 environment consisting of one server. I now have a new one for Ex2010. How far can I deploy Ex2010 CAS without disturbing message flow to old Ex2003? If I don't modify DNS or firewall settings, can I complete the Ex2010 installation and have Ex2010 running while waiting for the weekend when I change the message flow to new server? Hi, If I understood your question well, you have SBS 2003 and you bought new server (no SBS) and you want to deploy Ex.2010. If I am correct then you have to remember that you will need deploy new DC and move on it all FSMO roles before you uninstall your SBS 2003 server. You can install new Exchange 2010 CAS role. If you will be install also HUB transport role then the Routing Group connector will be installed automaticly to communicate between Ex. 2003 and 2010, but if you will have no users on Ex.2010 you can not worry about mail flow. Petr Weiner

You can deploy exchange 2010 server by normal means into exchange 2003 environment ( taking usual protection for windows 2008 dc etc). even if you bring on Cas, Hub or mailbox server into the environment it will not affect the Exchange 2003 server. Creating the exchange 2010 mailboxes on new server will start the functionality of mailflow through HUB and Client availablity of only those mailboxes on 2010 through CAS.

Hello, I hope the following article is helpful for you: http://www.simple-talk.com/sysadmin/exchange/upgrade-exchange-2003-to-exchange-2010/ In the Exchange 2003 and Exchange 2010 co-existence environment, you must use Exchange 2010 as the Internet Facing server. Thanks, Simon