Mailing Standards of the United States Postal Service Domestic Mail Manual > 200 Commercial Letters, Flats, and ParcelsDesignStandards > 270Commercial MailMedia Mail and Library Mail > 274Postage Payment and Documentation
1.0 Basic Standards for Postage Payment
2.0 Mailing Documentation
The mailer is responsible for proper postage payment. Mail manifested using the Electronic Verification System (eVS) under 705.2.9 must be paid with a permit imprint. Postage for Media Mail and Library Mail may be paid by any method (see 604) except precanceled stamps. Pieces with postage affixed must bear the correct numerical value of postage for which the piece qualifies. Permit imprint may be used for mailings of nonidentical-weight pieces only if authorized by Business Mailer Support at USPS Headquarters.
See 203.1.0 and 203.2.0 for postage statement and documentation standards.