HCW8001 Unable to determine the Tenant Routing Domain

Hi, @M Dwight Snow

Thanks for posting your question in the Microsoft Q&A forum.

According to your description, you have encountered error 10025 [Client=UX, page=Configuring, fn=RunWorkflow, Thread=31] HCW8001 Unable to determine tenant routing domain, please try to add coexistence domain to on-premises Exchange x.mail.onmicrosoft.com. According to the error message, the coexistence domain mentioned is a possible cause. I would like to confirm with you whether it is possible to try, and provide the following information:

1. Are you using hybrid deployment? If yes, you can check the prerequisites and check whether Enable is selected on the Federation Trust page.
2. After HCW runs, is your Direct Sync turned on? If yes, stop HCW and rerun to check the results again, and enable directory synchronization through the command.

Set-MsolDirSyncEnabled -EnableDirsync $true

1. You can also use the command to manually add the routing address for the user and then rerun HCW.

Set-AdUser username -Add @{ProxyAddresses=('smtp:[email protected]')}

Refer to: Hybrid deployment prerequisites | Microsoft Learn

If you have any questions, please feel free to contact me. If the answer is helpful, please click "Accept Answer" because it can help other members of the Microsoft Q&A community who have encountered similar problems and are looking for solutions. Thank you.

Best,

Jeanne

I tried that info before i posted, and MS O365 support has been slow to assist.

Melvin