University admission application deadline date?

It said everything must be received by Deadline date. I did submit my application, but what if I haven't submitted supplemental materials(transcripts) by that date?Can I just go to the post office and ask them to postmark the deadline date and send in the transcripts even if it's a day late?|||Mail it out as soon as you can and have them mail it overnight. It depends on the university and how many applicants there are if its one day late. Typically, more prestigious and selective universities will not accept the transcript one day late.|||I would send it in asap, colleges want customers, so they will accept every good applicant.