Migrating Exchange to a New Domain


When teaching about Exchange Server 2007, many questions about migration and transition from old messaging platforms arise. Coming to E2K7 from GroupWise, Notes, and other systems naturally have a number of factors to be considered, yet even coming to E2K7 from earlier versions of Exchange Server involves many possible approaches and choices. The following question is not uncommon.

We are in the process of moving to a new domain. I’m being told to look into what would be the best way to move/migrate all the users over to the new domain. One of the recommendations is to build a new Exchange box on the new domain and then move all the mailboxes over to the new Exchange server in the new domain.


My first question is “Is the new domain in the same Active Directory forest as the first?”

My second question is “Will the old domain still exist after the migration?”

Without the answers to these questions, I could describe a few scenarios leading to different directions and rather dissimilar tactics and final solutions.

However for the moment, I’ll assume that you’re talking about using a separate forest and that the original domain (and perhaps forest) will no longer exist after the migration. That’s not all that unusual – I’m not saying that everyone does that, but it’s not uncommon either.

Migrating Mailboxes to Another Forest

When the target domain is in another forest, it is also in another Exchange organization because in Exchange Server 2007 each Active Directory forest can support one Exchange organization and that messaging organization structure is based on and tied to the forest. Also, domain rename of Active Directory is not currently supported with Exchange Server 2007 installed in the forest due to some hard-coded FQDNs. Those are probably some of the reasons such a migration has been recommended to you.

  1. Establish network connectivity between the forests.
  2. Associate the two forests at a domain name system (DNS) level.
  3. Consider trust relationships between the forests.
  4. Establish Exchange Server(s) in the new environment if you haven’t already done so.
  5. Configure the proper connectors for mail flow between the Exchange environments.
  6. Move mailboxes over to the new environment, creating the user accounts along with them.
  7. Move public folders if you have them to the new environment.
  8. Move any relevant connectors from the old environment to the new.
  9. Consider the exit plan for decommissioning the old environment.

This list isn’t a strict guide, just a possible overview of one approach to the process. Let me know if you have questions on details or whether all of these aspects are necessary for your plan. I hope this helps!

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