Are they snail-mailers or is the new theory assuming that whoever got decisions today aren't SDN'ers?
Good question, I just checked last year's thread and they got their emails well ahead of any mailed letter.
Rejections came first via e-mail, then waitlist/acceptance e-mails.
Last year it wasn't really a "rolling" process persay- they sent a batch out in Nov then another batch in Jan and March. And as far as I can tell, everyone received decisions in those batches... didn't see any early interviewers get deferred and get a decision months later. The only exceptions were those who interviewed near the a batch release date usually had to wait until the next batch.
However, this year they may be changing the process up? From what I can tell, last 2 years they didn't send this email at all... and this e-mail makes it sounds like Mt. Sinai sends acceptances all the time between now and march, rather than in just a few batches.
I'm basing this all on analysis of threads of yesteryear lol so take it with a grain of salt.. I'm just really neurotic cause this is my #1 school and i have too much time on my hands.
Systematic error seems probable lol

or like others have said, they are changing things up and no longer have a true waitlist.
Like I said, this email is a new thing this year and regardless it appears that everyone got some kind of decision in the past... no individual's decision was deferred to a later batch.
very interesting.. just gotta wait and see