We have all of our mailboxes in Exchange Online. MX records point to Exchange Online. Autodiscover points to Exchange Online (autodiscover.outlook.com).
These were migrated to O365 from a previous project (previous supplier).
I have a new on-premises Active Directory forest. I have configured AADConnect server and will be syncing my new AD users to Azure.
I will also be hard matching the Exchange Online mailboxes to my on-premises AD users (using immutableID command. Not an issue).
As I have installed a new Exchange 2016 environment, I want to see the Exchange Online mailboxes visible in my on-premise Exchange ECP.
I want to do this without having to set up a Hybrid Configuration. The reason is, There is no need for Free/Busy, no need for mail to route across on-prem and EXO - because, Autodiscover points to Outlook.com, MX records point direct to Exchange Online.
I just want to be able to see the Exchange Online mailboxes displayed as "Office 365" mailboxes in my on-premise Exchange 2016 so IT admin team can do BAU activities such as changing Exchange related attributes (e.g. hide from address list) etc from on-prem. Or even be able to create a new remote mailbox from Exchange on-prem.