What is the minimum height for any mailpiece?

The minimum height for any mailpiece is indeed 3 inches. This measurement is essential for ensuring that mail can be processed efficiently through USPS facilities. Mailpieces below this height may not be able to be automatically sorted by the processing machinery, which could lead to delays or additional handling requirements.

This minimum height requirement also aids in maintaining consistency and reliability in mail delivery and processing. By adhering to standard dimensions, USPS can optimize its systems and speeds, as different sizes and shapes of mailpieces can create complications during sorting and delivery.

The options provided include other measurements, but 3 inches is the smallest allowable height for a mailpiece to be considered valid for mailing, ensuring it fits the operational capabilities of the postal service.