IUG Listserv Restrictions
If an e-mail is sent to the list from a non-subscriber, the message is discarded and the sender is not notified.
If a message is sent by a list subscriber, it is automatically processed by the list software without listmaster review. (The restricted list status is not the same thing as a moderated list.) The e-mail address must match exactly (with the exception of capitalization -- e-mail addresses are case-insensitive), including the entire hostname portion, to determine whether the message comes from a list subscriber.