I guess I found out how to do it :-)
I just needed to run the Remove-MailboxPermissions
command:
Remove-MailboxPermission -Identity user -User mike@example.com -AccessRights FullAccess -InheritanceType All
where user
is the mailbox I want to "hide" from Mike.
I have run the command with different -Identity
arguments as many times as the users in the domain... obviously skipping Mike's own user.
Finally, I checked that the list of users on which Mike has permissions was empty, by running:
Get-Mailbox -ResultSize unlimited -Filter "(RecipientTypeDetails -eq 'UserMailbox') -and (Alias -ne 'Admin')" | Get-MailboxPermission -User mike@example.com
Hope it will help somebody!
Cheers,
Guido