What to understand first
USPS free supplies are helpful when they match the mail class and service. The seller should avoid treating every free box as interchangeable. The package choice still has to fit the product and the shipping method.
Small-seller planning questions
- Does the product fit the free package without wasted space?
- Does the service match the packaging?
- Would a plain box or mailer be cheaper or more flexible?
- Does the product need inner protection against moisture or bending?
Size and weight still matter
USPS has size and weight rules. Use current USPS guidance before pricing large or heavy shipments, especially when a package approaches length-and-girth limits or special pricing conditions.
Useful official pages to confirm details
Carrier rules, service names, and supply availability can change. Use the current carrier page before setting prices or packaging standards.