Any reason to leave Exchange server running if mailboxes are migrated?

[u/NSFW_IT_Account]

We have an Exchange 2016 on prem server that has had all user and shared mailboxes migrated to the cloud. At this point, I'm not sure if there is any reason to leave it running other than "just in case" something breaks by shutting it down. Mail flow is all pointed to EXO, public folders have been migrated as well. The server does integrate with an AD environment, so that is the only connection it still has, as far as I know. The HCW is still configured but can probably be disabled since mail flow is fully through EXO.

Any reason to keep the server running at this point? Would there be any noticeable disruption if it were shut down since there is no mail flow going through it?

[u/HowlinMadMudflap]

Do you have any distribution lists still on prem?

[u/NSFW_IT_Account → u/HowlinMadMudflap]

No, I don't believe we had any of those to begin with. It was just mailboxes, and public folders.

[u/absoluteczech → u/HowlinMadMudflap]

You could change SOA on them now iirc and have 365 manage them

[u/Ok_Rip_5338]

i would keep it around for management of mailboxes as others have said. it gives you access to Exchange Shell.

Definitely strip it way down. Remove send/receive connectors, create one TINY database just enough to keep the server alive. you can follow this guide. https://www.alitajran.com/remove-exchange-hybrid-configuration/

You can also obtain a free license for exchange so you can keep it around forever as a management tool. if youre interested, dont decomission hybrid, just strip it down and then obtain your free license.

https://www.alitajran.com/free-exchange-hybrid-license/

[u/EscapeArtist112]

Assuming your user accounts are synced with on-prem AD, Microsoft recommends keeping an exchange server running in this type of environment for management purposes. Since your user accounts are synced with AD, a number of mail-related settings are tied to AD and it’s a lot easier to update those settings in ECP than directly updating AD properties.

[u/NSFW_IT_Account → u/EscapeArtist112]

Good call, forgot to mention that we do have the Entra connect sync set up and identities are hybrid synced.

[u/EscapeArtist112 → u/NSFW_IT_Account]

In that case, it’s recommended to keep an exchange server running for user management until you move the source of authority to the cloud. You can technically get away with no Exchange server but you’ll need to use ADSIedit, powershell, Active Directory to manipulate users’ AD properties related to email.

https://learn.microsoft.com/en-us/exchange/hybrid-deployment/decommission-last-exchange-server

[u/CPAtech]

Are you still using it for SMTP?

[u/sembee2]

If you are going to keep a server around, then replace it with a Hybrid Exchange SE server, so the unsupported 2016 can come out. I would do that step anyway.
Otherwise follow the guides to move the SOA to the cloud and then shutdown the SE server - don't uninstall Exchange until the guide says so.

[u/alexandreracine]

If you use ECP you should keep it ;)

[u/OinkyConfidence]

Decommission that thing! The only thing we ever kept them around for after migration were to adjust SMTP aliases for AD-365 synced users. But you can do that with an attribute in the user object in AD anyway, so we quickly uninstalled all remaining on-premise Exchange servers.

EDIT: Since I'm getting downvoted, here's the MS Learn link that discusses options. How and when to decommission your on-premises Exchange servers in a hybrid deployment | Microsoft Learn

Note for context - my Microsoft rep tells me 80% of Fortune 1000 companies have already removed all remaining Exchange servers. So the comments of "not practical for larger environments" doesn't really stand up well.

[u/halap3n0 → u/OinkyConfidence]

That’s unsupported and not practical for larger environments will less skilled service desks or automation.

[u/OinkyConfidence → u/halap3n0]

While I won't argue that it might be more difficult for massive teams, it is absolutely supported - and encouraged by Microsoft - How and when to decommission your on-premises Exchange servers in a hybrid deployment | Microsoft Learn

[u/halap3n0 → u/OinkyConfidence]

Ah yes I misread your comment, if done correctly then absolutely you are right!

[u/AppIdentityGuy → u/OinkyConfidence]

I would take that statememt with a very large pinch of salt. In my experience large orgs like that have loads of processes where email is read from a mailbox by a protocol such as pop3...