What's the difference between "Waiting" and "Promoted" in the dashboard?
When people register onto your list they are put in the waiting list. Optionally, you can "promote" them and put in a different list. But why would you want to do that?
Imagine you are hosting a competition where every week the top 5 on your list win a prize. Every week you want to reward these 5 people but also remove them from the list so that next week they won't win again.
Subscribers moved from the Waiting list to the Promoted list won't receive an email so it's still your responsability to inform them.