I have been speaking to a friend of mine recently. He mentions in our conversation how the United States Postal Service is the courier of a certain package he got in the mail, and yet it was returned to the original sender. Apparently he got something that one of his parents did not like, so it was sent back. My friend is wondering what the "return tracking ID/number" is, so he visited his local post office and a postal worker there said that there is no sort of return tracking ID/number involved for this mail package. The worker said that the original tracking ID is all that is needed; this worker checked the package's history and saw that it was delivered to my friend's house with the original tracking ID, yet no return tracking ID was used in the entire process. My friend is lost for words. What should he do now? I mean, is there any method available to discover what happened during the course of the mail delivery back to the original sender?