I recently moved out of state but my grandma still lives at my old address. A few days ago she informed me I received a package which was marked as undeliverable with my full name and address as the return sender, so she was wondering if I sent something which I hadn't. Inside was just a packing slip with something about a whatnot giveaway and a username. I searched the app, signed up and saw the user had already been removed from the platform.
Today, she let me know I received another returned package which just contained basically the back you pull off the shipping label and a handwritten letter actually addressed to me. The letter said they don't know what I was trying to send but the package they received contained two of the backings to the shipping label, like the other returned package I received. They said they find it very interesting and if I'd like to chat about it to contact them at a phone number. My question is what kind of scam is this? I'm assuming the handwritten note is part of the scam.