I know I used to be able to ship liquid products, as long as they were sealed in a waterproof container (like a sealed plastic bag, with enough absorbent material to absorb all the liquid if it did leak).It was explained to me that they did not want any leaking liquid damaging their sorting machinery for example. know I used to be able to ship liquid products, as long as they were sealed in a waterproof container (like a sealed plastic bag, with enough absorbent material to absorb all the liquid if it did leak).