Mailing

Beginning July 1, 2025, the United States Postal Service (USPS) will prohibit the use of rubber bands, twine, and string to secure bundles of flat mail. This rule is aimed at reducing mail breakage and processing delays caused by loose or unstable bundles.

WHAT DOES THIS MEAN?

• Definition of Flat Mail: In USPS mail, a “flat” refers to pieces larger than a letter but smaller than a parcel. Think magazines and large manila envelopes. A flat must be more than 6-1/8 inches wide OR 11-1/2 inches long OR 1/4 inch thick. 
• Bundling Flat Mail: A bundle is a group of addressed mail pieces that a mailer assembles and secures together before mailing. The individual pieces in a bundle are presorted for delivery to a special area. Bundles of flat-size mail pieces are secured with banding, shrink-wrap, or a combination of the two. Banding may include clear plastic bands that maintains enough tension to keep the bundle intact during processing. Wire or metal banding is not permitted. The address block on the bundle — containing all address information, including the optional endorsement line and any barcoded, pressure-sensitive, bundle label — must be visible and readable to the naked eye. If shrink-wrap is used, it must be transparent and seams or imperfections such as heat creases should not appear over the address block. If banding is used, it cannot obstruct any part of the address block. Tight, clear, smooth banding will never obstruct the address block.

• Rubber Bands and Twine Prohibited: Traditional rubber bands and twine/string can no longer be used to secure bundles of these flats. USPS has eliminated these materials due to their tendency to slip or break, which jeopardizes bundle integrity and causes rework. The only exception is for First-Class Mail flats in flat trays, which may continue to use rubber bands or twine if necessary. Going forward, mailers must use more secure banding methods for nearly all presorted flat bundles.

• Mandatory Cross-Strapping of Bundles: All bundles of flat mail must now be secured with at least two bands applied crosswise (perpendicular to each other), or alternatively be shrink-wrapped with one or more banding straps encircling the bundle’s length and girth. This ensures bundles can withstand normal transit without breaking apart. (The only exception is for newspaper bundles entered under “exceptional dispatch” in flat trays, which may be secured with just a single strap around the bundle’s middle)

• Heavier Strapping for Carrier-Route Bundles: For presorted flat mail prepared on Enhanced Carrier Route (ECR) pallets or bundles, any shrink-wrapped multi-carrier-route bundle must be secured with two or more cross-strapped bands for extra stability. This update  ensures that even shrink-wrapped bundles have additional banding to keep them intact during handling.

• Small Flat Mailings Exempt from Bundling: Mailings of 500 or fewer flat-sized pieces entered at a Business Mail Entry Unit (BMEU) no longer require bundle preparation. Such small-volume mailings may be placed loose in flat trays instead of being bundled.

These changes are officially documented by USPS and take effect July 1, 2025 (even though the printed DMM will be updated on July 13, 2025). The new standards emphasize that bundles must be able to withstand normal transit and handling without breakage. These new USPS requirements mean that mail centers and fulfillment operations will need to upgrade their bundling methods, or risk rejected shipments, delays, or compliance issues.