We are seeing some trends where quite a few customers are migrating mailboxes to a new Exchange organization, in a different Active Directory (AD) forest. This blog post is aimed at helping to explain the fundamentals of what is required to move mailboxes across forests so that you can be prepared with the correct data, make better plans, and successfully perform a migration without encountering painful problems. The blog post doesn't cover how to setup and configure shared address space or Free/busy.
After reading this blog post, you should have better understanding of:
- How to plan your migration by understanding your current forest configuration and your desired configuration.
- Different ways for you to synchronize user data between different AD forests.
- Networking and Administrator permissions required to perform a successful cross-forest mailbox move.
Read more at source: http://msexchangeteam.com/archive/2010/08/10/455779.aspx