Question about pre-paid return postage
I am sending some baseballs to a former college athlete (no one famous, just someone for my personal collection) and I want to pay for the return postage. This is easy when sending something like a baseball card, since you can just include a SASE. Is there an easy way for me to do this with something larger like a box holding 2 baseballs? Do I have to join something like stamps.com or is there an easier way?