If you realize that you have made a mistake after printing postage, but before mailing the item, you can apply for a refund. The types of refunds are:
Regular refunds, also known as physical refunds. These are refunds for non-tracked items within 60 days of the date shown on the indicium. These refunds require physical submission of the original mailpiece.
Electronic refunds, also known as E-Refunds. These are refunds for domestic labels with an Intelligent Mail barcode (IMb) or Intelligent Mail package barcode (IMpb), or international labels printed using an integrated customs form layout. The request for an electronic refund must be within 30 (thirty) days of printing the label. After this 30 (thirty) day period, you can no longer request a refund.