They allow you to pay a $.30 "Rigid" surcharge in a plain envelope. Why allow a rigid envelope if you are not allowed to ship anything rigid in that envelope? They are free to make whatever rules they like but they need to train their people in what the correct rules are. If more people would point out the rules to the cashiers or postmasters and get an explanation of why they think the envelope should be a package maybe we would win a few more battles.