Then use that letter to prove instate tuition!
Its probably a good thing to advise people to do before they get here. Sending a bit of mail to themselves so they have proof of address.
I had a credit card with terms that were too good when they changed the laws a few years ago, so they were cancelling the card, but said I could get any other card. I had recently moved into a buddies house, I paid him rent but had no utilities. The credit card was even mailing my bills there. When I went to get a new card with them, they refused me because I had no utilities at that address and wanted proof I was who I said I was. WTF, I had the old card for 8 years and they were even billing me there! I get offers from them all the time now, but I'm not going back to that company ever.