Remove On Premises exchange Hybrid and go fully Online

[Keith Caines]

Hello,

I currently have a scenario where there is a Hybrid Exchange environment with 1 server. All my mailboxes have been migrated online.

I would like to completely remove dependency on local AD and I do not care about AD synchronization.

How do I "tell" the O365 tenant not function on it's own so that I can manage 100% from 365 Administration?

I do understand that my MX and other DNS records will need to be changed.

Are there any solid guides out there on decommissioning the on premise exchange server. I want to do this with the least impact on users.

Thanks,

Keith

[#2]

@Richard_Pettigrew Pretty cool if supported

[#3]

I have almost the same question as the OP, @Keith Caines (well done starting conversation that lasted 2 years bud!). I am re-asking the question specific to Minimal Hybrid configuration

Scenario:

• Exchange 2010 with Minimal Hybrid configuration
• No need for ongoing sync AD with Azure/365
• All mailboxes have been moved to 365

At this point what is the process to retire Exchange safely and correctly? As I understand it...

1. Replace DNS records with 365 tenant info
2. Remove Service Connection Point from 2010 (AutoDiscoverServiceInternalUri) 
3. Turn off directory synchronization 
4. Uninstall Exchange

Am I missing anything? I'm trying to be careful because minimal hybrid does not have connectors and organizational sharing (IntraorganizationConnector & OrganizationRelationship) mentioned in the MS decom document.

Also AAD Connect does not have "Exchange Hybrid" configured.

One more thing, I'm not sure about is Remove-FederationTrust is not mentioned in the MS decom document and I dont know why.

So there are a few differences from retiring a full hybrid deployment and I dont want to leave some mystery setting in there that could bite us later. 

I really appreciate whatever confirmation or advice you have! Thanks!

[#4]

Can just recommend this blog post:

https://petri.com/hafnium-highlights-the-problem-with-removing-the-last-exchange-server

[#5]

For anyone coming here, this is now possible since 2019 CU12: https://docs.microsoft.com/en-us/exchange/manage-hybrid-exchange-recipients-with-management-tools