Hatemail is armor constructed by a prisoner and made from the thousands of hateful letters sent to them by their victim's family. The hate filled letters are so many in number that the prisoner has a steady supply of materials with which to forge the hatemail. Similar to chainmail in form and function, hatemail is used to stop knives, shivs and shanks from piercing vital organs. The hatemail covers the prisoner's abdomen, sternum and chest and is light weight and easy to buiild.
Charles Manson was attacked by a fellow prisoner but his hatemail armor protected him and stopped the shank from entering his flesh. Shannon Tate's family sent Charlie all the supplies he needed to forge the hatemail. The irony is killing them.