The United States Postal Service (USPS) has approved new 2015 postal rates that begin Sunday, May 31, 2015. The 2015 cost of sending a 1-ounce USPS Certified Mail letter with Return Receipt (old fashioned green card) will cost $6.74. If you send Certified Mail using Electronic Delivery Confirmation the cost is $4.69. USPS Mail Service: 2014 Rate VS: 2015 Rates: