We currently have a domain with two AD sites. Site A has one Exchange 2010 server which currently holds all the mailboxes. I set up the new site, Site B, and it is connected via site-to-site VPN. Site B has one new Exchange 2010 server and zero mailbox databases as of now.
I did set up a mailbox database on Site B server and moved a test user's mailbox from Site A server to make sure that the mailbox move feature works, and then quickly deleted it after verifying that.
The goal is to keep the same DNS info (autodiscover, MX, OWA, etc) but to migrate the mailboxes and public folders from Site A server to Site B server, and then decommission the Site A server.
What would be the best way to achieve this without causing interruption in mail service?
EDIT: The current plan is to switch DNS to point to the new Site B server and then slowly migrate the mailboxes over to it as well. The main concern is that the server in Site A will continue trying to send mail for clients and will be rejected because the DNS will no longer be configured correctly for it. The second concern is that Outlook clients will need to be reconfigured to point to the new server's hostname.
Best Answer
Steps to move Exchange 2010 servers to the new AD Site:
Foe more refer to this blog
Best practices on how to move Exchange Server Safely with minimum downtime. http://msexchangeteam.in/moving-exchange-server-2010-from-an-active-directory-site/
Moreover, you may also get help from this Exchange migration solution to move user mailboxes and public folders between exchange server environment.