Corrugated packaging can be shipped by air, truck, or rail.
Because carriers accept liability for the product they transport they can refuse to ship something inadequately packaged. If you want to have your product insured by the carrier it is best to follow their regulations.
Shipping "in boxes" means a corrugated or solid fiberboard container (as defined by Item 222 of the NMFC and Rule 41 of the UFC). These are quality standards. These rules give material specifications that vary depending upon the total gross weight and the dimensions of the box and its contents.
Boxes that follow the above standards must have a circular box stamp or certificate. Items shipped in cartons without the proper "box cert" may not be insured by the carrier.
A box, as defined by the carriers, is an enclosure that has at least six sides and has an opening that is only large enough to insert one's fingers to rip open a flap. It must also be capable of passing a qualified drop test. Boxes must be made of a combined board that meets minimum burst strength and combined basis weight, or the appropriate edge crush test per the appropriate gross weight and dimensions.
The air cargo and airline industries do not publish detailed packaging instructions except for special articles such as live animals, human remains, seafood, etc. Individual carriers - UPS, Fed Ex, the US Postal Service, and others -- publish their own tariffs. Both UPS and Fed Ex require compliance with Item 222. Also, both require that the packages they carry are of minimum 200 burst strength or 32 ECT, and are capable of meeting International Safe Transit Association (ISTA) -- Pre-shipment Testing Procedures. It is best to check with the carriers themselves to determine if there are any special requirements.
The DOT (Department of Transportation) regulates the packaging and transport of hazardous materials. All aspects of a package that will contain hazardous material must be certified and cannot be changed once certified.
Package manufacturers are responsible for manufacturing a quality product that conforms to material and performance specifications of the test and certified design, and for correctly formatting all regulated markings.
Packaging regulations for hazardous materials can be found in 49 CFR,§§ 171-178.