My company is looking at the following scenario:
We have 2 Active Directory domains in the same AD forest: DOMAIN1.COMPANY.COM and DOMAIN2.COMPANY.COM. BES1 is in the DOMAIN1; there are uses on BES1 from both DOMAIN1 and DOMAIN2.
The domain DOMAIN2 is to be collapsed, and all DOMAIN2 user accounts/mailboxes will be moved to DOMAIN1 using Microsoft's Active Directory Migration Tool (ADMT).
This is an Exchange 2007 environment with BES 4.1.6.

Will all BES users moved from DOMAIN2 to DOMAIN1 need to re-run Enterprise Activation on their device after their accounts are moved?

they should NOT have to be reactivated. They're in the same Exchange org, same GAL ... just do a handheldcleanup after you get them moved.

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