USPS Flat Bundling Rules 2025: Your Essential Guide to Strapping & Wrapping
Mastering the New USPS Flat Bundling Rules: Your Essential Guide to Strapping & Wrapping in 2025
If you’re a commercial mailer, the time for preparation is over. The new USPS flat bundling rules for 2025 are now in full effect. The days of securing your mail bundles with a simple rubber band or a piece of twine are gone, and compliance with the new strapping requirements is mandatory.
These changes were made to improve the speed and reliability of the USPS processing network and to reduce damage to your mailpieces. This guide will break down everything you need to know about the current mail preparation standards, making it easy to understand what’s required and how to keep your mail moving without a hitch.
The Biggest Change: Goodbye to Old Tying Methods
Let’s get straight to the point. For most commercial flat mailings (like USPS Marketing Mail® and Periodicals), the following are no longer permitted for securing bundles:
- Rubber bands
- String
- Twine
Using these materials on your bundles will likely lead to your mail being rejected or returned, causing costly delays to your campaigns and communications.
The New Standard: Cross-Strapping & Shrink-Wrapping
The USPS has standardized two primary methods for securing flat mail bundles. Understanding these is key to your mailing success.
1. Plastic Cross-Strapping (The Preferred Method)
This is the new gold standard for mail preparation. Bundles must be secured with plastic strapping that is tight enough to keep the mailpieces from shifting. Most importantly, you must use a cross-strapping technique.
What is Cross-Strapping?
The cross-strapping requirement means applying at least two plastic straps:
- One strap running along the length (the longest dimension) of the bundle.
- One strap running along the girth (the shorter dimension) of the bundle.
The straps must cross over each other on both the top and bottom of the bundle, creating a secure package that won’t fall apart on automated sorting equipment.
2. Shrink-Wrap (The Alternative Method)
You can also use shrink-wrap to secure your bundles, either by itself or in combination with strapping.
Specifications for Shrink-Wrap:
- Clarity: The shrink-wrap must be transparent so that the delivery address, markings, and barcodes on the top mailpiece are clearly visible and readable.
- Strength: It must be strong enough to prevent the bundle from breaking open during handling.
- Seams: The seams of the wrap should be placed carefully to avoid obscuring any part of the address block or postal markings.
Do I Even Need to Bundle Anymore?
This is a critical part of the new rule that can save you time and money. In some cases, you may not need to bundle at all!
For certain mailings, the USPS now allows mailers to place loose (un-bundled) flats directly into mail trays. This is generally permissible for:
- Full trays of barcoded mail for the same 5-digit or 3-digit ZIP Code™.
- Some smaller mailings where bundling is no longer mandatory.
Always check the specific USPS flat bundling rules 2025 for your mail class, as eliminating the bundling step entirely could be a major operational win.
Quick Reference: Do’s and Don’ts Checklist
| Do ✅ | Don’t ❌ |
|---|---|
| Use plastic cross-strapping for bundles. | Do not use rubber bands, string, or twine. |
| Use clear, strong shrink-wrap as an alternative. | Don’t use opaque or weak shrink-wrap. |
| Ensure straps are applied around both the length and girth. | Don’t use a single strap in only one direction. |
| Check if your mailing qualifies for loose packing in trays to skip bundling. | Don’t assume you must bundle every mailing. |
| Refer to the official Domestic Mail Manual (DMM) for specifics. | Don’t rely on old habits or outdated information. |
Official USPS Resources and Links
Don’t just take our word for it. It’s crucial to review the official source material from the USPS to ensure full compliance with the current strapping requirements.
- USPS PostalPro™ Website: The ultimate resource for commercial mailers. The bundling and strapping rules are detailed here.
Visit USPS PostalPro - Domestic Mail Manual (DMM): The specific regulations are written here. The primary sections to review are for your mail class.
DMM Section 204.3 for Periodicals
DMM Section 245.3 for Marketing Mail - USPS Guide to Mailpiece Design: The Mailpiece Design Analyst (MDA) team provides free consultations and can answer specific questions.
Contact an MDA
Conclusion: Adapt Now to Avoid Delays
Adapting to the USPS flat bundling rules for 2025 is essential for uninterrupted mail service. These changes represent a significant operational shift, but they are designed to create a more robust and efficient mail system for everyone. By adopting the cross-strapping or shrink-wrapping methods and checking if you can eliminate bundling altogether, you can ensure your mailings remain compliant and are delivered on time.