Forum Discussion
Decommissioning Last Hybrid Exchange Server – All Mailboxes in Cloud, Still Using AAD Connect
Hi all,
We're currently running a hybrid Exchange environment with AAD Connect in place. All user mailboxes have already been fully migrated to Exchange Online, and Exchange Online is handling all mailbox mail flow. The only thing left on-prem is the last Exchange 2019 hybrid server, which we want to decommission.
Our current setup includes:
AAD Connect for syncing identities from Active directory to Entra
Exchange 2019 hybrid server (used only for recipient management and SMTP relay)
An SMTP relay connector used by on-premises applications and printers
No mailboxes hosted on-prem
Our plan:
Decommission the on-prem Exchange server
Install the Exchange 2019 CU12+ Management Tools on a domain-joined server or admin workstation to manage recipient attributes
Replace our on-prem SMTP relay with an Azure-hosted relay
Questions:
Has anyone here successfully removed their last Exchange hybrid server while keeping AAD Connect in place?
Do we have to just turn off the last physical server and not uninstall exchange server 2019 ?
Any gotchas or issues managing recipients via the new Exchange Management Tools post-decommission?
Does Microsoft still recommend keeping an Exchange server in this case, or is the Management Tools path fully supported now?
Would appreciate any insights or lessons learned from folks who’ve gone down this path. Thanks in advance!
8 Replies
Hi AshJor
If you still have synced users from on-premise active directory you should keep at least one Exchange server to be able to edit Exchange attribute on on-premise active directory.
For your information synced objects in Entra ID cannot be modified from Azure portal , you can modify it only from on-premise Exchange server or active directory.
For more information please read this Microsoft article:
https://learn.microsoft.com/en-us/exchange/decommission-on-premises-exchange#why-you-may-not-want-to-decommission-exchange-servers-from-on-premises
Hi Moustafa-Sherif
With Exchange 2019 CU12 you can use Recipient Management and don't need Exchange Server anymorehttps://learn.microsoft.com/en-us/exchange/manage-hybrid-exchange-recipients-with-management-tools
thanks for this update.
The details are outlined by Microsoft in the below articles:
Hi Dan,
When it says not to uninstall the last Exchange server, does it mean not to uninstall the Exchange server software? Can I just power off the virtual machine (VM) that the Exchange server resides on and then delete the VM, or do I need to keep the VM and just power it off?
You can delete the VM. You don't need to keep an offline Exchange server around.
Hi AshJor
>Do we have to just turn off the last physical server and not uninstall exchange server 2019 ?
Yes exactly
https://blog.icewolf.ch/archive/2022/04/27/install-and-use-exchange-2019-cu12-recipient-management-powershell/
>Any gotchas or issues managing recipients via the new Exchange Management Tools post-decommission?Make sure, your other systems (IAM, Automation, Ticketing Tool, etc) are able to work with the Recipient Management. You can't use a Remote PowerShell to connect to Exchange anymore. You need to be able load the Commandlets
Kind Regards
Andres
One of the details is that after turning off the last Exchange server and before running the Active Directory Cleanup script, the recipient management command will still try to connect to the Exchange server for admin audit logging, resulting in an about 40 second delay for the command execution.
