My feeling is the email for sure definitively means one thing: you havent been waitlisted or rejected yet so I'll take that. And if you didnt get the email, its still too early in the game for dings/WL (for NYU at least) so I wouldnt take the lack of email to mean that you're about to get bad news.
Overall, I think that if admissions wanted us to know that we were held, waitlisted, rejected, they would just do it. They have no need or incentive to send secret subtle messages in vague general emails or to give us hints of impending doom. Since we're all vying for spots its easy to forget that the schools are also competing with peer institutions, some of whom have a very fast turnaround time or a more predictable admissions process (i.e. standard timeline for most applicants across the board, predictable decision waves, etc.). I think we should all try to take what the email says at face value, that we should be assured that they're diligently reviewing applications and thats it.