Marc,
Thing is, these people are bona fide subscribers. But their mail is not
showing up in the moderation queue, at all.
In fact, in the example user whose message I sent, his message hit the
moderation queue, I told him to subscribe, he subscribed and
re-submitted ... and now the message isn't going through, but it isn't
showing up in the moderation queue, either.
--Josh Berkus