As Richard says, there's no way to get a quick count from the admin
interface. It certainly isn't "most" of the 1510 subscribed addresses,
despite all new subscriptions being moderated by default.
Looking at my archived messages for this week, it appears that we
average 2-3 held messages per day, which normally get passed along
within a few hours at most. I try to unmoderate people as I can, but
quite a lot of people subscribe, never post, and just stay there. More
power to them, of course.
Wikimedia-l mailing list, guidelines at: