Decommissioning Exchange 2013 Server in a Hybrid Deployment with AD Connect

[almarlibetario]

Hello Everyone,

Apologies if this has been asked many times somewhere but I need to clear up some possible ways to resolve this.

I got this scenario where we have a customer with existing Exchange 2013 on-premise server, AD Connect, and AD running on W2K12R2 and we managed to fully migrate every user to O365 using Hybrid Migration. DNS records are now pointed to O365 and no other activities are being done in on-premise exchange.

Now, we are trying to eliminate the Exchange 2013 server. I have read a lot of articles already saying we need to keep the last exchange server just to manage the exchange attributes on-premise because of the SoA. And it is the only method that is supported by Microsoft.

I know this is partly true because as I experienced before we got a customer that did not make a clean uninstall of the Exchange server and when we tried to sync the AD Users to O365 using AD connect we encountered some errors on the exchange attributes and I had to manually clean all of those (Thanks to powershell).

My question is this, is it possible if I disable the AD Synchronization to O365 first then Uninstall the Exchange On-premise Server and clean all the exchange attributes in AD then re-run the AD Connect and do a Softmatch of the AD users to the O365 users? Will this help me get out of that attribute thing from Exchange?

Your opinion is highly appreciated. Stay Safe everyone.

Regards,

Almar

[#2]

@almarlibetario 

The short answer is no i'm afraid.  What it boils down to is that if your are synchronising your AD to O365 and are using Exchange Online - then you need to have an Exchange server to remain in a supported position, and manage on-premises attributes and SMTP relay.

That is not to say that it doesn't work without the Exchange Server.  It certainly does and I've had a few customers make that choice.  The Exchange Management Server is purely there to make your life easier and keep you supported. 

I tend to put in an Exchange 2016 server for this and decommission older Exchange servers.

[#3]

Hi @PeterRising, thank you for your response. Agree, I really believed the setup will work without the exchange but had to compromised being on the Microsoft's unsupported lists.

[#4]

@PeterRising 

@almarlibetario 

Hello, I am being asked to decommission our exchange 2016 server. I get conflicting information, so it sounds like its do-able but not supported. Correct?    

I do have all mailboxes off on prem. We just use Ad Connect, so I guess I need to find step by step directions on how to do it if we did go that route.  My one question I have and I don't know if you know the answer. I read somewhere that you have to create the users in AD on prem and then create it in the cloud for email.  How do you sync them?  Maybe I need to post this as its own question?  Thanks