Utilities: List Settings: New Subscriber Policy settings control how people join your list. You may:
-Specify whether new subscribers must confirm their memberships by responding to a confirmation message, or confirm when they unsubscribe.
-Determine how secure your list is--can anyone join? Do they require a password, or is it private? Or can members only be added by an administrator? Can people subscribe by email, or only through the ListManager web interface?
-Specify who can or cannot join your list.