An ice pack won't break. The mailed jiaozi will not deteriorate if it is frozen in an ice pack, and the food contains more water. It takes 3-5 days to post them. During these 3-5 days, it was sealed and unventilated. In this case, food is most likely to breed bacteria and deteriorate and rot. Tangyuan is a traditional food of China Lantern Festival, which has different names and production methods due to regional differences.