We have just completed a staged migration from a single Exchange 2003 Server to Exchange Online (Office 365) using the guide, "Perform a Staged Migration of email to Office 365."

At the end of the guide, Microsoft warns: Decommissioning Exchange can have unintended consequences. Before decommissioning your on-premises Exchange organization, we recommend that you contact Microsoft Support.

The following have been accomplished so far:

• All on-prem mailboxes have migrated successfully.
• All on-prem users have been converted to mail-enabled users.
• Their mailboxes no longer exist in Exchange 2003, as part of the conversion to MEUs.
• DirSync is used to synch AD up to Office 365.

We plan to:

• Decommission Exchange Server 2003.
• Upgrade domain controllers from Windows Server 2003 SP2 to 2012 R2.

Since Exchange 2003 doesn't work in 2012 DFL/FFL, it most likely isn't possible to use any 2003 management tools to edit ADUC.

In this scenario, would you recommend to simply uninstall Exchange 2003?

Thanks!

• Edited by AMSYS 16 hours 43 minutes ago