Mailers who wish to request a refund for an overpayment of postage should contact their local Post Office®, unless the refund request is for a mailing presented under a Special Postage Payment System (SPPS). Refund requests for mailings submitted under SPPS should be submitted with all supporting documentation to SPPSRefunds@usps.gov. A list of documents required to be submitted for refund requests is posted on RIBBS® at https://ribbs.usps.gov/bma/documents/tech_guides/SPPSRefundProcess.pdf. If the refund request pertains to a MERLIN® appeal, presort error, double payment, problem loading Mail.dat® files into PostalOne! ®, metered mail, precanceled stamp mail, nonprofit Standard Mail®, delayed mail or any issues that do not involve an SPPS, it first should be submitted to the local Post Office where the mailing was made.