Advice with O365 Cutover migration aftermath

[Maxell]

Hello,

 

I am in the process of migrating our on-prem Exchange 2010 setup to O365. So far, I have:

 

• Created and successfully completed a cutover migration batch
  
• Installed and successfully configured DirSync with passwords
  
• Tested accounts to make sure I can login with on-premise AD credentials
  
• Monitor incremental sync, which is running fine each day
  

 

Next week, my intention is to:

 

• Make required DNS changes to change mail delivery to O365
  
• Monitor this until I am happy it is working
  
• Delete migration batch
  
• Uninstall Exchange from our on-prem server and enable me to re-use the server elsewhere
  

 

It is the last point regarding removing our on-prem Exchange server which is causing me headaches. I thought it would be straight-forward, but I have now read lots of conflicting articles about what the impacts of removing this could be.

 

I am using Exchange 2010, the DirSync is running from Server 2012 R2. Has anyone else been through this process with a cutover migration? Microsoft say removing the Exchange server should be fine, but others say that this will remove Exchange attributes from the on-prem AD which will then sync to O365 effectively disabling the users mailbox.

 

Can anyone help to stop my head spinning?