Please could someone assist me with the following issue. So, I got an Exchange 2010 hybrid environment with a few mailboxes migrated to Office 365, and they are listed as remote mailboxes in Exchange 2010. One my clients right clicked on one of these remote mailboxes and chose to disable it. Now the mailbox exists in Office 365 but no longer as a remote mailbox on-premise. Migrated users can find his email address in the GAL, but on-premise Exchange users cannot. The AD account is still in place. What would be the best way to resolve this? So that the migrated user shows up as a remote mailbox in the Exchange 2010 organisation and on-premise users can find him in the GAL. Appreciate any advice.
For the missing remote mailboxes repairing you will need to have the ExchangeGUID of those O365 mailboxes. Get-mailbox is the proper ps commandlet in the EXO order to you have these attributes. For the repairing process you do not need to revoke and reassign the used O365 license for the affected users.
Fixing process the following:
1. Recreate the remote mailbox for the affected users
The remoteroutingaddress will be your tenant mail service domain. If it is done the recreated remote mailbox will have ExchangeGUID attribute with null value. Then you will have to overwrite this with the mentioned ExchangeGUID of the user O365 mailbox.
2. Fix the remote mailbox ExchangeGUID
Set-RemoteMailbox SAMACCOUNTNAME -ExchangeGUID <Copy from Office365 Exchange GUID>
3. Make manual ADconnect delta sync.
Then your users are able to use desktop outlook again.