Unrelated to my original post, but I have been on a quest to purge all the junk from my physical mail. It is a huge PITA, but in almost all cases you can email someone and eventually get them to stop.
The other big ones that cut a lot of junk are DMA choice for catalog opt out (https://www.dmachoice.org/register.php) and the pre screened credit card offer opt out (https://www.optoutprescreen.com/).