Thank you for your response.
I am aware of that option. It is indeed how we cope with the situation currently. However maintaining two separate lists where one is only accessible to an admin is highly inconvenient, especially with many customers.
Would it be possible to add the option in user attributes that when a user gets set to inactive you have a checkbox “add mail to filter as well” so an agent would be able to access both lists.
Or expand e-mail filter macros, so you can implement an e-mail filter based on Custom user objects e.g. one creates the user object “Banned” with a checkbox, now when setting up an e-mail filter it does not only look for e-mail parameters, but it can also compare the mails to the custom object which if active ignores the users e-mail request automatically.