Amazon declined to comment for this story, but the USPS issued the following statement: “Dedicated Postal Service employees across the country are committed to delivering for the American public and have fostered the recent package growth through exceptional performance. Growth in our package business partially off-set the significant decline in mail and is essential to help stabilize the finances of the Postal Service and pay for our infrastructure that enables us to fulfill our universal service obligation. Like any prudent business, we do not publicly discuss specifics of our business relationships.”