[MM3-users] Block members from sending cc's and bcc's

Hi everyone,

Using Mailman 3 with Affinity web interface and we want to stop our members from sending to cc: or bcc:

We've found the Header Filter and cc and bcc appear in it. Tried to configure it to "hold for moderation," but it hasn't worked. Partly because we don't understand what to put in the Pattern input box. I put in cc: because it requires something.

Can anyone advise?

Cheers, Cathryn