Just an anecdote, but a professor I had been emailing with notified me a few weeks after the application deadline had passed that one of my LORs hadn't been received. He told me to get it in ASAP so that the committee could look at my file. I went to the prof who had written the letter, and he resent it. It actually turned out to be their administrative error as he had mailed, emailed, and faxed the letter to them, but it would have gone undetected had this faculty member not been on top of my application. Letter went in, two weeks later I was accepted.
I will say this about email, though, it seems easy for it to hurt you as well, to come off as pretentious, overly solicitous, or just inarticulate (to some degree I would think faculty members anticipate a hint of these qualities in such emails). This probably doesn't matter so much when the prof isn't on the adcomm, but it might cast a pall on your file if you do have a poor exchange with someone on the adcomm. I mean, 200-300 applications is a lot, but considering that far fewer of those 200-300 actually make contact with professors, you will probably leave some lasting impression if you do (and of course if they reply and engage you).