Introducing Cloud-Managed Remote Mailboxes: a Step to Last Exchange Server Retirement

Can I safely uninstall my last Exchange Server after enabling IsExchangeCloudManaged?

Hi all,

Looking for confirmation from anyone who has already gone through this process successfully.

Environment:

• Exchange hybrid previously configured
• All mailboxes fully migrated to Exchange Online
• Still syncing identities from on-prem AD via Entra Connect
• On-prem Exchange server has been powered off for about a month with no issues
• Mail flow is fully cloud-based
• I am managing aliases and mailbox attributes directly in Exchange Online

I have set:

Set-Mailbox <user> -IsExchangeCloudManaged $true

on all mailboxes, and this appears to be working correctly. I can now manage aliases directly in EXO PowerShell and the GUI even though users are still synced from on-prem AD.

I’ve been following these Microsoft articles:

Decommission on-prem Exchange

Removing your last Exchange Server FAQ

Introducing Cloud-Managed Remote Mailboxes

My question is:

Is it now fully supported/safe to completely uninstall the final on-prem Exchange server while continuing to sync users from on-prem AD?

Specifically:

Are there any remaining dependencies I should check first?

Has anyone hit issues after uninstalling?

Are new licensed mailboxes working normally after uninstall?

Any gotchas around aliases, proxyAddresses, or remote mailbox attributes?

Thanks.