By default, when you create a mailing list, everyone may send correspondence to this list. If you need to configure a mailing list that only members are allowed to send mail to, you can do this through the WEB Mailman interface.
To configure a mailing list that only members are allowed to post to:
- Log in to the WEB Mailman interface as the list administrator.
- Enable the Restrict posting privilege to list members option.
Note: By default a mailing list is created with the Posts must be approved by an administrator option enabled. That means all messages must be approved by the moderator before they are posted to the list. Therefore, if this option is disabled and unwanted mail is posted to the list, you can re-enable it and moderate incoming messages.
For more information, please see Mailman documentation at: http://www.gnu.org/software/mailman/docs.html.