Permit sending to distribution lists only to authenticated users
Is there any way Zimbra can be configured to permit sending mail to distribution lists only to authenticated users?
The problem I have is that we have a distribution list with many addresses from the outside of the organization. Now, I just figured out that one spammer sent mail to this list and the mail was delivered to all recipients. As all our distribution lists are only used by members of the organization, the best solution, and most secure, would be to allow sending mail only to authenticated users.