Exchange migration to o365 from on-prem 2016 exchange

I setup a hybrid migration to o365 exchange.  The migration of all the mailboxes, groups and public folders is complete.  There were many issues with the migration, but in the end, its all online now.  During the migration process i setup ADConnect and synced AD with o365, there are currently no DirectorySync errors showing( all issues were addressed ).

I would like to decommission the on-prem node.  Its a Hyper-v VM running windows 2016 ( exchange 2016 ).  The AD is local to the hyper v environment.  Its a small setup, 2 AD servers, a file server, sql 2016 server and iis server ( all VMs ).  The host server is a stand alone server not connected to AD.  The idea here is to completely remove the exchange locally, exchange is uninstalled and removed from the domain per normal removal procedures.

My concern here is that MS says you should keep the server running, even if its just acting as a relay.  I need the resources back, so i need the server gone.  I am also concerned about having to update it and backups.  With these in mind, it needs to go.  Unfortunately, microsoft says that you need the on-prem for control of the user accounts.  I dont see why, local AD can service them.  The ADConnect install is on the DC, not the exchange server, so syncing should continue.  The email portions of the accounts is completely controllable from the o365 exchange admin.  I am trying to understand the exact reason the on-prem needs to stay.  Why have it setup to migrate all your data online, then demand i need to keep the local one?  If this is a must, is there a way around this?  I dont want to break AD and the email piece nor make this more difficult to maintain.
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Jose Gabriel Ortega CastroCEOCommented:
The point is that exchange server manages a series of properties for all the user's that are required for the correct functioning of exchange server as a system (ex: targetAddress attribute and proxyAddresses, you can see them enabling the Advanced Features (View/Advanced Features) in AD U&C, in the attribute tab of any user).

Another valid point is that autodiscover service allows the redirect from "on-premises" to cloud but it doesn't work the other way, as you can see autodiscover is the most useful service on exchange server system.

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Naveen SharmaCommented:
If you have Dirsync and your objects are being synced from on-premises to Office 365, then you should have one Exchange on-premises.

Get in detailed here: Office 365 and Dirsync: Why should you have at least one Exchange Server on-premises

Migrate smoothly and swiftly from on-premise Exchange Server to Office 365:
BrentDevOpsAuthor Commented:
From what i found, we can use ADSI or powershell and dont need the exchange on-prem.  I was more looking for someone who did this and can confirm it as an alternative to keeping the local one.  There is also mention of installing the Essentials Experience role and using that.  Not super fun options from what i can see, but better than continuing to run something that is going out of date.  Thoughts?
Guy LidbetterCommented:
Hi Brent,

In short, you can use ADSI Edit, but it's not supported (also a huge manual pain in the ****). So if you are happy with that, it's your (Or the Businesses) call.

Here's straight up answer from MS regarding this...
Seth SimmonsSr. Systems AdministratorCommented:
No comment has been added to this question in more than 21 days, so it is now classified as abandoned.

I have recommended this question be closed as follows:

-- Jose Gabriel Ortega C (https:#a42445992)
-- Naveen Sharma (https:#a42446016)
-- Guy Lidbetter (https:#a42464289)

If you feel this question should be closed differently, post an objection and the moderators will review all objections and close it as they feel fit. If no one objects, this question will be closed automatically the way described above.

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