OK adding my two sents worth, I don't think anything that thay may send will say slave ID on the envilope, and if you do have the ID tatooed onto the slave it does depend were it is done if most people can, and wil see it. There are plases on the slaves body that can and are covered with clothing for the vanila world when out and about, even to the beach. If you don't want to be outed and you do want to be marked, or you Master/Misstress wants you marked than tryone of these plases. Just get the tatoo in a different town were no one knows you. and wil do it there thats all. That an cet your curage up to expose yourself a bit to a stranger for the mark.