I sent my commitment deposit check for Macaulay Honors at Hunter College on April 30, 2016 and confirmed that the post office lady postmarked it for that day. Is the deadline postmarked by May 1st 11:59 P.M. or RECEIVED by May 1st 11:59 P.M.?
Usually when a deadline is over a weekend there is a grace period until Monday. I don’t think you have a thing to worry about. I also think they go by postmark. That’s how the IRS does its deadline.