How to Decommission Exchange Server: A Guide for Admins
IT administrators regularly search for ways to decommission Exchange Server after they migrate their data elsewhere. This removal process is a natural part of the lifecycle of an on-premises email server like Microsoft Exchange.
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However, not many are aware of the best practices to follow while uninstalling the last remains of a dead Exchange Server from their organization’s infrastructure. That is why I have curated this guide. Here, I will explain the exact steps you need to follow for a safe and successful disconnection. Before we begin, let’s understand what exactly we mean by retiring a server.
What It Means to Decommission Exchange Server & Why Do It?
Decommissioning, in simple terms, is the process of removing Exchange Server. You are not just powering down a server but rather uninstalling the legacy software and cleaning up the databases.
Sometimes admins have no other choice but to update the existing AD configuration, like the upcoming Exchange 2016 and 2019 end of life happening in less than 1 month.
Decommissioning almost always begins after you migrate Exchange Server to Office 365 or upgrade to a newer version of the on-premise system.
Moreover, if you fail to decommission the server properly, it can cause serious mail flow issues.
This is especially true if there are still some hidden remains of a previous Exchange generation.
What would happen is that instead of receiving the emails in the new environment, emails will continue to accumulate inside the older environment.
This can also result in lingering “orphan” objects in Active Directory that no admin wants to see. Not to mention, this kind of semi-dead infrastructure is the exact type of vulnerability that hackers look to exploit.
You don’t want your organization to face an attack that happened in 2021. Where Hafnium attacks targeted on-premise Exchange servers, impacting an estimated 250,000 systems globally.
Nevertheless, decommissioning is a perfectly doable process. However, at the same time, its multi-stage nature means you can’t just hit a decommission button and be done with it. There are quite a few prerequisites that an admin needs to ensure that their organization is adhering to before beginning the removal. Let’s see what these are.
Prerequisites to Fulfill Before Decommissioning Exchange Server
Start by checking your Exchange Server version and build number. This will help you estimate how much time you have left before the official support ends.
Here is a miniature timeline showing you the exact end date of the most recent editions
| Exchange Server | EOS Date | Current Status |
| Exchange Server 2013 | April 11, 2023 | Unsupported |
| Exchange Server 2016 | October 14, 2025 | Support Ending |
| Exchange Server 2019 | October 14, 2025 | Support Ending |
Ensure that all data has been safely migrated from the Exchange Server you are about to retire to the correct destination. It could be a new on-premise system or Office 365. If you have completed this task and the manual method feels too hard, use a renowned utility like the SysTools Exchange to Office 365 Migration software.
Download the demo and transfer the data with speed and accuracy.
Once the migration is done next most important job is to remove database copies. Many organizations maintain mailbox database copies. So to prevent leakage of critical information, delete them as well. You can use the EAC or the Remove-MailboxDatabaseCopy PowerShell cmdlet to do that.
Rearrange the MX records, Autodiscover, and other DNS entries to point towards the active servers. This is a mandatory step to be done irrespective of where your new system is, Exchange SE or Exchange Online. Accompany this with the timely removal of all old/dead Send/Receive server connectors.
If you operate a hybrid setup, a critical decision must be made. Which is to decide whether you are going to use this decommissioning to fully transition onto the cloud or still maintain some presence on-premises.
The final check is to see if you have the correct role and administrator permissions with Exchange Organization Management rights. Check and have the Exchange setup files ready for uninstallation.
Steps to Decommission Exchange Server After Migration to Office 365
The biggest reason for so much confusion at the time of decommissioning is the lack of consistency. Every organization has a unique environment; that’s why if you try to copy someone else’s guide that you read about in a decade-old forum, you might get stuck.
Instead of doing that, here is a plan of action applicable to all Exchange on-premise servers that have moved to the O365 cloud:
Begin the end of your on-premise server by pointing everything to the cloud; even your MX and Autodiscover DNS records should now point towards Microsoft 365.
Disable and remove the on-prem SCP. Use PowerShell commands to stop the Service Connection Point.
Log in to the Exchange Online admin center, and delete all the hybrid connectors you find that are still joined to the dead on-premises Exchange. Also, close the organizational relationship.
Finally, disable directory sync to make your users truly “cloud-native.”
Remove your Exchange by running the official uninstaller from the Windows Control Panel.
How to Decommission and Uninstall Exchange Server 2019
For Exchange 2019, the process is clean but requires attention to detail.
- Prepare the Server: Before you do anything, check for and delete the health mailboxes in Active Directory Users and Computers (ADUC). If you have any public folder mailboxes, you must remove them first with the Disable-Mailbox <Mailbox ID> -PublicFolder command.
- Remove Databases: In the EAC, make sure all mailbox databases on the server are dismounted, and then delete them.
- Run the Uninstall Command: Do not use the Windows Control Panel. For the most reliable removal, open an elevated command prompt, navigate to your Exchange 2019 setup files folder, and run the command: Setup.exe /mode:Uninstall
How to Decommission and Uninstall Exchange Server 2016
Decommissioning Exchange 2016 is similar, but you have to account for its DAG features.
- Remove from DAG: If your server is part of a Database Availability Group (DAG), you must formally remove it first. Use the Remove-DatabaseAvailabilityGroupServer cmdlet.
- Delete Health Mailboxes: Just like with 2019, search for and remove the Exchange 2016 health mailboxes in ADUC.
- Run the Uninstall Command: Once the server is prepared, use the same command from an elevated command prompt in the setup files folder: Setup.exe /mode:Uninstall
How to Decommission and Uninstall Exchange Server 2013
With Exchange 2013 being past its end-of-support date, decommissioning it is a high priority.
- Migrate All Content: Double- and triple-check that no mailboxes, archives, or public folders remain.
- Delete Health Mailboxes & Databases: Follow the same process of removing health mailboxes from ADUC and deleting the databases via EAC or PowerShell.
- Uninstall: You can use the Control Panel for 2013, but the command line method is often more reliable: Setup.exe /mode:Uninstall
Conclusion
This is how you decommission Exchange Server flawlessly. Here we say that to remove the server, you must follow a certain checklist. Not doing that will expose you to all sorts of problems, ranging from missing emails to hacked infrastructure. Also, because a successful migration out of the current Exchange infrastructure is such a crucial prerequisite of decommissioning, you must choose the correct way out. Which is none other than the utility we told you about earlier.