Can USPS supplies be used differently than the intended use ?

[TriPolar]

Non-consumable packages like mail bags and heavy cardboard and plastic boxes are property of the USPS and are supposed to be returned to them, just like milk crates.

[Terry_Kennedy]

@gaffa

Both FedEx and UPS employ the USPS for so-called “last mile” delivery, basically admitting that the much-maligned Postal Service is better at the job than they are.

No, they offer it as an economy-grade service (UPS Mail Innovations / FedEx SmartPost). Less expensive (but sometimes not by much) than USPS Priority Mail, but slower.

[PastTense]

Misuse of USPS supplies can result in fines from the US government, as well as unhappy eBay customers and bad feedback.

USPS Priority Mail supplies are free from the post office. They may only be used for priority mail. Continued misuse may result in the post office charging for these supplies in the future. The disclaimer on every priority mail box and envelope states,

“This packaging is the property of the united states postal service and is provided solely for use in sending priority Mail shipments. Misuse may be a violation of federal law. This packaging is not for resale.”

USPS Rules for Packaging eBay Items