To disabled the clutter feature in a user’s O365 mailbox run the following command:
Turn off Clutter for single user
Get-Mailbox –identity firstname.lastname@example.org | Set-Clutter -enable $false
Set-Clutter -Identity <user name> -Enable $false
If you want to disable this feature for all users in your tenant as an admin, you can do this with PowerShell.
1. Connect to Exchange Online using PowerShell with an admin account.
2. Run the command below.
Get-Mailbox | Set-Clutter -Enable $false
Turn off Clutter for ALL users
Get-Mailbox -ResultSize Unlimited | Set-Clutter -Enable $False | FL