If you need boxes in bulk, you can order them for free on the USPS Postal Store.

Sometimes sells lots of boxes or pre-packed "shipping kits," though it's often more expensive than getting them directly from the source.

You can get for free directly from the United States Postal Service . Because these boxes are intended to encourage the use of Priority Mail services, the Postal Service provides the physical packaging at no cost—you only pay the flat rate shipping fee when you actually mail them. Where to Get Them 📦 Local Post Offices