Amazon’s status as the U.S. Postal Service’s biggest customer could be about to change.By completing this form, you agree to receive marketing communications from PYMNTS and to the sharing of your information with our sponsor, if applicable, in accordance with our Privacy Policy and Terms and Conditions .Complete the form to unlock this article and enjoy unlimited free access to all PYMNTS content — no additional logins required.The tech giant has begun to scale back the volume of packages it ships via the ...