Mailing Standards of the United States Postal Service - Domestic Mail Manual > 200 Commercial Letters, Flats, and ParcelsDesignStandards > 220 Commercial Mail Priority Mail > 225Mail Preparation
1.0 General Information for Mail Preparation
3.0 Preparation of Permit Imprint Mailings
4.0 Preparing a Commercial Plus Cubic Mailing
Priority Mail packaging provided by the USPS must be used only for Priority Mail. Regardless of how the packaging is reconfigured or how markings may be obliterated, any matter mailed in USPS-provided Priority Mail packaging is charged the appropriate Priority Mail price.
When sealing a Flat Rate Envelope, Flat Rate Box, or Regional Rate Box, the container flaps must be able to close within the normal folds. Tape may be applied to the flaps and seams to reinforce the container; provided the design of the container is not enlarged by opening the sides and the container is not reconstructed in any way.
The sender‘s domestic return address must appear legibly on Priority Mail pieces.
The marking “Priority Mail” must be placed prominently on the address side of each piece of Priority Mail. See 202.3.3 for price and other markings.
To use a permit imprint, the pieces must be of identical weight and, unless all the pieces are in a weight category for which the price does not vary by zone, the pieces must be separated by zone when presented to the Post Office, except under 3.2.
A permit imprint may be used for mailings of nonidentical-weight pieces only if authorized by Business Mailer Support at USPS Headquarters.
Commercial Plus cubic mailpieces for multiple price tiers may be combined in the same container.