This CSR discusses the standard for enclosing printed Standard Mail enclosures in a Periodicals publication.
When Standard Mail is enclosed with a Periodicals publication mailed at Periodicals prices under the provisions of Domestic Mail Manual (DMM) 703.9.3, the Standard Mail enclosure, if printed matter, may exceed the weight of the host Periodical provided it is no heavier than 300% of the weight of the Periodicals publication. For example, a four (4) ounce Periodical may be prepared and paid as Periodicals mail and be accompanied by a printed Standard Mail enclosure or enclosures weighing no more than twelve (12) ounces with applicable Standard Mail postage paid on the enclosure(s). The same principle does not apply to Package Services pieces since such mail may not be combined with a Periodicals publication in a combination price or mixed class mailing. In addition, this guidance does not apply to First-Class Mail enclosures; materials that would otherwise qualify as Standard Mail, but are combined with a Periodicals publication and mailed at the ride-along price; or material mailed as an enclosure with a Periodicals publication at Standard Mail prices that is not printed matter. Such materials may not exceed the weight of the host publication.