How to move an Exchange domain to another AD forest

Posted on 2014-12-19
Last Modified: 2015-01-19
Hello Experts,

I have a new project for the early part of next year which involves the "splitting" of a company, as such they want to remove one of their Exchange accepted domains and add it to another organisation in another AD forest. There are too many users to simply "flick a switch" and migrate across in one go so there will need to be a migration period where some users on the new domain have mailboxes on the old system using Outlook Anywhere and some will be moved to the new mail system. The organisations are physically located at different offices but linked by fast, fibre VPN links. From a high level view I see my options as either;

1. Setup the new AD domain with the new Exch, add users to the AD and Exch, import their data to the new mailbox from their local OST file, delete their mailbox off the old Server and create an SMTP connector to pass unknown local mail to the new Exchange Server, then once all users migrated simply change the MX record to the local circuit/IP address.

2. Setup a trust between the organisations, try to carry out mailbox moves, once all mailboxes, users etc moved to the new domain simply break the trust and remove the accepted domain from the old Server.

Any suggestions/guidance? Not too concerned with specific detailed steps; (unless someone has them handy?) but more pointing in the right direction. I don’t think public folders etc a concern in this instance, only email/mailbox data needs migrating.
Question by:markfurey
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Accepted Solution

Satya Pathak earned 167 total points
ID: 40509216
follow the below KB it might be help you .
LVL 63

Assisted Solution

by:Simon Butler (Sembee)
Simon Butler (Sembee) earned 333 total points
ID: 40509247
There is a third option available to you.
Build a new Exchange server in the existing domain. Move all users to that new server.
Then break the link, isolating the two sides. Clean up the domain correctly for Exchange (recover the removed server, remove the mailboxes, uninstall Exchange) and for AD (Removing the removed DCs).

It does work, but is a completely clean split - nothing can move between the two sites as it will be confusing.

Otherwise a cross forest migration would work. This is documented on TechNet pretty heavily. Ensure that everything is on the latest version/update level and try and have them on at least Exchange 2010 SP3 on both sides.


Author Comment

ID: 40531097
Thank you for all your responses, I think I will keep it simple and setup a new domain at the customer’s site with Exchange, then move users across to the new Domain 1 PC at a time, update their profiles and add the new Exchange account with send connectors setup to allow mail-flow between mailboxes on the old and new mail-server during the transitioning stage. One question though which I have yet to lab out, they all have recent versions of Outlook which allow for multiple Exchange accounts, would it be possible to setup two Exchange accounts in Outlook with the same address? The reason I ask is because the main task I'm completing is to setup the new AD Domain and Exchange in a VM with active replication for failover, internal IT are then going to takeover Exchange migration once its setup and mail-flow etc working, if I can add two different Exchange accounts with the same email address within Outlook, I'm guessing they could then just copy data from the original OST file to the new Exchange mailbox?
LVL 63

Assisted Solution

by:Simon Butler (Sembee)
Simon Butler (Sembee) earned 333 total points
ID: 40534429
Moving data within Outlook can work, I have done it myself. It is very labour intensive though, as it means visiting each machine.


Author Closing Comment

ID: 40558102
Thank you all for your comments, in the end  I just needed to install the new Server's, configure mail-flow between the new and old Server's and internal IT were going to decide on a "migration plan" which sort of got me "off the hook".

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