"Postmark"?

Ok, so I have finally decided on which college I am going to this fall. The deadline to submit Intent to Enroll, test scores, and transcripts is this Sunday May 1st at 11:59:59 pm. Yesterday I submitted my AP Scores, and mid year high school transcript. However, on the University’s webportal, it still says it’s not there yet. Their policy is that it must be postmarked by May 1st (this Sunday) in order to not have a rescinded application. Am I ok? Will my application be rescinded?