So I ordered a few packages last week, and got a card through my door saying the packages had to be signed for. I haven't done any DNM shit for a while, and I was under the impression that you were to NEVER sign for packages. So I shit myself.
However it turns out that all of my packages were sent special delivery (even though I didn't request that from the vendor), and since there were several of them my postman decided to require a signature even though I don't think that is technically required for special delivery. I went to the post office and picked up my packages without incident.
So I encourage you to ignore conventional wisdom and just sign for anything that comes, as otherwise they'll open the package to try and find the sender's address and then you're DEFINITELY fucked.
They won't open up a package to find the senders address, the senders address should be on the outside of the pack, obviously it won't be a real address and it will end up who knows where...