If you want to be a hardass, force 'em to SKYPE you when they need a few bucks! That way, at least you can lay eyes on 'em on occasion! You're entering the zone of "I'm Independent and I Need Some Walking Around Dough!!!" Not quite as bad as puberty...but only just!

Nowadays, you don't have to send an envelope, the colleges have debit cards that the sucker parents can "plus up" so the little angels can buy their cokes and snacks and schoolbooks! They've got the whole "separating the 'rents from their cash" thing down to a fine science~~!