I wonder if there isn't some confusion, as a result of trying to use the CNC mailing list manager?
It is certainly possible, as Rich notes, to run a moderated list, which only allows subscribers to post to the list. However, when I went to the CNC and started to set up a mailing list, I don't see that so plainly stated. As a matter of fact, I don't see that option at all.
However, I do see the option to allow/not allow subscribers to subscribe on their own.
OTOH, the AOTA tutorial here:
seems to indicate a list that would do exactly what Maynard wanted in the first place:
allow only subscribers to post, and require manual intervention of the moderator in order to process subscriptions.
The only disadvantage that I see here, is that it would also require manual intervention in order to unsubscribe, as well. It would probably be possible to set up some special e-mail address, or web form, where subscribers could go to/write to when they wanted to unsubscribe, and automate the unsubscribe process via a script of some type.
At least, this sounds easier to me than installing ezmlm-idx.