They govern the mail, by Act of Congress, as enumerated in the Constitution. That you don't seem to like the USPS or its operations doesn't make it not a gover

They govern the mail, by Act of Congress, as enumerated in the Constitution. That you don't seem to like the USPS or its operations doesn't make it not a government service. Some countries have no government postal service, and some have no postal service at all, but the US clearly has a government postal service.