vinny

I have an app out with a due date of Dec. 1 (tomorrow). My three letters of recommendation have been submitted through their online system, but no one at the graduate college has uploaded one of them to my file, so it looks like one still needs to be completed. I'm sure this uploading won't happen until Monday (Dec. 2nd) and my question is, do their systems generally stop accepting documents to be uploaded after the deadline so they know everything they have was submitted on time? Or are uploaded documents time stamped so they can see it was done before the deadline? My concern is that if no one does this until the 2nd, my application will be considered late.