you can put delivery confirmation on nearly everything package-wise, except international. But you do get some proof of sending when you do international, just can't track it. Priority mail is a fast, and middle of the road in pricing method. Express is super fast and super expensive, ground is super slow and cheap.. heheh.. so you don't necessarily have to use the priority box, but you should check the weight/dimensions/distance and see what it would be with a normal box, vs what it would be with the priority box if you are tight for money. Sometimes it's a lot cheaper if it's not going far and isn't very heavy, to use a normal box.