For air shipment purposes, magnets are considered "dangerous goods" and the International Air Transport Association's (IATA) Dangerous Goods Regulations (DGR) must be followed.
In order for magnets to be shipped by air:

Flux measurements of all packages containing magnets must measure less than 0.00525 gauss 15 feet from the package. (If flux measurements are less than 0.002 gauss measured 7 feet from the package, the package is not considered to contain magnetic material, and hence is not classified as a Dangerous Good. However, unless the packaging is extremely secure and there is no chance that the contents will shift or shielding will be damaged in transit, it is safer to proceed as though the package comes under the DGR.)

Packages containing magnetic materials must be clearly identified according to Packing Instructions 902. This calls for a "Magnetized Material" label to be affixed, and for a Shipper's Declaration of Dangerous Goods to be provided to the carrier.

Personnel responsible for shipping magnets by air are required by the Federal Aviation Authority (FAA) to be trained for that purpose and for those training records to be maintained.

Contact your carrier for more information and guidelines.

Note that in addition to transportation costs, Dangerous Goods fees apply to each package shipped by air, making shipping magnets by air quite costly.

Packaging magnetic materials for air shipment must be accomplished considering the above. Powerful magnetic components and assemblies need to be shielded so that magnetic fields will meet air shipment criteria. Packaging may need to be designed using Finite Element Analysis methods.

Thus re-packaging or re-arranging packaging certified for air shipments will void the original certification.

An example of how magnetic fields can be contained is illustrated in the FEA models below.
Unshielded Magnetic Field     Magnetic Field Contained by High Permeability Box Around Magnet
Unshielded Magnetic Field     Magnetic Field Contained
by High Permeability Box Around Magnet