[Administrativia] Posting rules: are messages silently dropped?

Messages I send from an email address which is not subscribed to nanog-post are apparently silently dropped. I do not receive a bounce (like it is typically the case when a list is closed) but, according to the archives, they are not distributed either (which may be good for the S/N ratio but I digress). Isn't it too harsh? <URL:http://www.nanog.org/email.html> explains how to post but does not mention what happens to posts from non-subscribers.