I came across an issue today where I needed to hide some old users email accounts that had been converted to shared mailboxes. However with our office 365 we don’t have full 2 way synchronization enabled. As a result when you go to the 365 portal and attempt to hide the user you get a big error message instead of a pat on the back for a job well done.
Instead what you need to do is:
- Go to a domain controller and fire up Active Directory Users and Computers
- Browse to the user in questions
- Right-Click on the user and select Properties
- Navigate to the Attribute Editor tab
- Locate the msExchHideFromAddressLists item and click Edit
- Set to False and click OK and then OK again to close and save the user changes
After this you will just need to wait for you AzureAD sync to occur and the changes to process.