In order for a postcard to be mailed, what shape must it be?

To be eligible for mailing as a postcard, the item must be rectangular in shape. The United States Postal Service (USPS) has specific guidelines for postcards, and among those is the requirement that they be manufactured or designed in a rectangular format. This shape allows for efficient sorting and handling during processing, which is critical for maintaining timely delivery.

In addition to the shape, postcards must meet certain size criteria to qualify for postcard rates. Rectangular postcards ensure standardization within the mail system, making it easier for automated machinery to process them efficiently. While there are various creative designs that can be produced for mailing, only those that conform to the rectangular shape and adhere to the postal guidelines will be accepted as postcards.