Mailpiece designers must prepare postcards from paper stock meeting the industry standard for a basis weight of 75 pounds or greater, with less than 71.25 pounds (measured weight for 500 25" by 38" sheets). The Postal Service does not recommended high-bulk stock. The stock must be free from ground wood unless coated with a substance adding to the stock’s ability to resist an applied bending force. A double postcard not prepared with all edges sealed must have the folded edge at the top or bottom. The open edge of the double postcard must be parallel to the address and must be secured with one tab (or other permitted closure) in the middle of the length. Pieces claimed at First-Class Mail automation card prices must meet the standards in the DMM.
