We are running Exchange 2010 on a Windows 2012 Enterprise server. We have a client that has changed their website address from www.acme.com
. They would now like to change their email address (about 30 users) to reflect the new address change (email@example.com). I would like to setup the new user accounts and still have the old email addresses available during the changeover. I believe that I would have to change the DNS pointers to have mail.acme.org and webmail.acme.org point to the exchange server WAN address. Can I leave the old address DNS pointers for mail.acme.com and webmail.acme.com? How would I make the users address change in the Exchange configuration and the ISP DNS pointer change?