M-bags are defined as direct sacks of printed matter (see 261.22) sent to a single foreign addressee at a single address. There are three types of M–bags: Airmail M-bags, International Priority Airmail (IPA) M-bags, and International Surface Air Lift (ISAL) M-bags. All M-bags are subject to the following conditions of mailing:
- Maximum weight of a sack: 66 pounds (including the tare weight of the sack). Lower maximum weights apply to certain countries. See the Individual Country Listings.
- Availability: All destinations that are referenced in the Individual Country Listings for Airmail M-bags, in Exhibit 292.45 for IPA M-bags, and in Exhibit 293.45 for ISAL M-bags.
- Identification: PS Tag 158, M–bag Addressee Tag, must be completed and attached to the neck of the sack.
- Postage: The applicable postage for Airmail M-bags, International Priority Airmail (IPA), and International Surface Air Lift (ISAL) must be affixed to PS Tag 158.
- Extra services: Certificate of mailing is available. Registry and insurance are not available.
Printed matter is admissible in M-bags. Articles that meet the definition of “printed matter” include newspapers, magazines, journals, books, sheet music, catalogs, directories, commercial advertising, and promotional matter. “Printed matter” is defined as follows:
- Papers upon which words, letters, characters, figures, images, or any combinations thereof appear.
- Papers that do not have the character of a bill or statement of account.
- Papers that do not have the character of current and personal correspondence.
Certain other articles may be enclosed in M-bags, provided that all of the following conditions of mailing are met:
- The articles being sent are limited to discs, tapes, and cassettes; commercial samples shipped by manufacturers and distributors; or other non-dutiable commercial articles or informational materials that are not subject to resale.
- The articles are related to the printed matter (see 261.21) with which they are being mailed.
- The articles are affixed to or are otherwise combined with the accompanying printed matter.
- For Airmail M-bags, the combined weight of each printed matter mailpiece and the related articles may not exceed 4 pounds. For IPA and ISAL M-bags, the combined weight of each printed matter mailpiece and the related articles may not exceed 4.4 pounds.
- The M-bag must be accompanied by a fully completed electronically generated PS Form 2976, which is to be affixed to PS Tag 158.
M-bags are not sealed against inspection. Regardless of physical closure, the mailing of an M-bag, including an airmail, IPA, or ISAL M-bag, constitutes consent by the mailer to inspection of the contents.