Not sure about it, but why go through so much hassle to leave the post office out of it. For packages you need to fill in a form, that is put on the package, and a copy goes home with you. I've sent a bunch of packages home in the last 2 years, and it really a 3 minute job at the post office. And to my standards, pretty cheap.
If you want to be sure it arrives, just go and post it at the postoffice.
A sender address is required, but ofcourse nobody is checking what you fill in there, if there is any reason to hide your send-from address.