DS16 makes money by doing tutoring. He's started ordering items online, most of the time they are from popular retailers such as amazon but sometimes they are from unknown retailers to me. There's been an influx of online orders by him recently. I've temporarily withheld his most recent package and I'm asking him to explain what he's buying. He said that I am being intrusive and it's "none of my business". I don't know how to proceed. I respect his privacy and so don't want to go through his mail however equally I am entitled to question what hes buying; teens like to experiment and push boundaries so chances are it could be something he shouldn't have. How should I proceed? Should I hand over the package to him or AIBU to at least question his purchases? I don't want to invade his privacy but equally I want to maintain safety.