I send some slides to the States for a show and they were just returned. I sent a self addressed stamped envelope to return them in, with $2.50 US postage on it. The stamps haven't been cancelled, but the envelope has a narrow strip of white paper on the front and back with some sort of a bar code on it. I have never seen anything like this. Has anyone else?
My question is - can the stamps be reused? There isn't a visible mark on them and I need stamps for another SASE.