Exchange Hybrid and that final Exchange Server

For those with an Exchange Hybrid configuration longing to remove the final server, a potential route is now available.

There was a recent announcement in the latest Exchange 2019 CU notes (Released: 2022 H1 Cumulative Updates for Exchange Server – Microsoft Tech Community) that states an update to how the Exchange Management tools role can be installed. This is important for Exchange Hybrid configurations. Essentially you can now install the Management Tools on a standalone server that does not have the Mailbox or Edge roles. This can then allow you to remove the final Exchange Server from on-premises and manage Exchange recipients through the Exchange Management Shell on the standalone server.

In essence, yes, you can remove the final Exchange Server from on-premises if that is all that remains in a Hybrid setup. However, the question remains, should you? Note that this is only possible if you install the latest Exchange 2019 CU12 update.

Impact

There will still be some impact of the removal of the last Exchange Server. In fact, guidance provided by Microsoft here, recommends that you do not uninstall Exchange from the server. Instead you should shut down the final server and then use some scripts to clean-up your environment. Why? Because by uninstalling Exchange you remove critical information out of Active Directory. This information is still required for you to manage your Exchange recipients through the EMS. The link above provides the process required to successfully remove the last Exchange Server.

Mail Relay

Now, this does not help for those who use their Exchange server for mail relay. If you want to remove the final Exchange Server then you will need to move mail relay. This could be to another SMTP server, but that seems to defeat the object of removing Exchange. Otherwise, it is possible to direct servers and appliances to send email direct to Exchange Online. Instructions on how to do this can be found here.

Conclusion

So, we can finally remove the final Exchange Server. Should you? That depends on the above factors. If you have no mail relay and want to remove the server, ensure you follow the guidance provided. If you use Exchange for Mail Relay, you will need to look to reconfigure all devices/applications that use Exchange to point to Exchange Online.

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