When sending any type of media, it is vitally important that it packaged carefully to avoid any further damage.
Place each drive in a seperate SeaShell container or an ESD (electrostatic discharge) bag.
Enclose the container/bag(s) inside a box with at least 5 centimetres between the media and each side of the box. The box should contain foam rubber, tightly packed foam pellets or bubble wrap. Please do not use screwed-up/shredded newspaper for the packing material.
Multiple drives in a single box MUST have at least 5 centimetres of packing material between each drive.