[MM3-users] Accept these non-members

Hi, list!

I have an announce only Mailman3 list. When I log into the web interface as an admin user, and go to the specified list, and choose Settings, I find the Message Acceptance tab. There, I find the edit field Accept these non-members. But this field is empty, although I know that some people have permissions and are able to post to this list. How can I find the list of these non-members and add more people or delete someone?

I'm running Mailman version 3.3.10, and mailman-web version 4.2.21.

Any hints?

Thanks, Lars