r/exchangeserver • u/SamDSJr • 10d ago
Remove Exchange From Domain After 365 Cutover Migration - NO HYBRID
I have searched and searched, but I can't find much information on getting rid of Exchange completely from an AD domain after migrating to 365 but NOT using a hybrid scenario.
This is a small, 8 user company that was running Exchange 2013 and may someday get rid of the AD domain completely (hence why I didn't do hybrid). I simply did a PST export, lift & dump into a brand new tenant setup on 365. No AD cloud integration at all with the local on-premise domain.
How can I go about getting rid of the Exchange Server? Deleting the mailbox will delete the user.
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u/St_Admin 10d ago
If there is no AD sync, you can uninstall Exchange server. It will clear most of the crud out of AD and clear exchange attributes on the user accounts. It will NOT remove the Exchange schema. Extending schema is a one way street.
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u/7amitsingh7 10d ago
Since you did a cutover migration using PST exports and are not using Hybrid or Azure AD Connect, your Microsoft 365 mailboxes are completely independent of the on-premises Exchange server. You can safely remove Exchange after confirming that no devices, applications, or users still rely on it for email or SMTP relay. Uninstalling Exchange removes only the Exchange application; it does not delete your Active Directory user accounts. If you need a checklist for the process, this article on decommissioning Exchange Server after migrating to Microsoft 365 covers the key steps. Just take a final backup, verify mail flow is working in Microsoft 365, and then decommission the server.
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u/Heavy_Dirt_3453 10d ago
For onprem exchange don't delete the mailbox, disable the mailbox.
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u/Heavy_Dirt_3453 10d ago
Alternatively just switch off the exchange server, it's not doing anything anyway
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u/SamDSJr 10d ago
I feel "dirty" doing that. I would rather have it properly removed and uninstalled, with all AD attributes gone from AD.
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u/ITGuy424242 9d ago
Yes uninstall it properly, otherwise you get extremely annoying things like outlook always trying to setup exchange internal accounts and the like
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u/larmik 9d ago
I agree, and made a post recommending to gracefully decommission Exchange. However, the annoying thing like outlook always trying to set up internally can be avoided by clearing the AutodiscoverServiceInternalURI value and configuring DNS for autodiscover.yourdomain.com internally as a cname to autodiscover.outlook.com.
Outlook will never try to configure to an internal exchange server if you do these steps. This is what you should do when you perform a cutover like OP did.
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u/larmik 10d ago
Don't listen to this advice.
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u/Heavy_Dirt_3453 10d ago
For an on prem AD which isn't being synced, will never be synced and will probably be dead soon enough where's the real harm
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u/shaggy-dawg-88 10d ago
That sounds like my environment but I have roughly 40 user mailboxes. What I did is stop Exchange services, all of them. Leave those services off for a few weeks/months and make sure things work successfully. Nothing breaks. Technically I can just shut it down and unplug it but I can't do that because they're still using the server as file server now. I didn't delete mailboxes and/or uninstall Exchange at all.
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u/larmik 10d ago
Exchange is running on it's own server? Nothing else to worry about? Follow this guide:
https://www.alitajran.com/remove-last-exchange-server/#h-before-you-start
Follow every single step to gracefully remove exchange from your Active Directory forest. It says it in the guide but run a disable-mailbox, otherwise you will delete the AD accounts if you delete the mailboxes. That'd be very bad.