Since I last posted, my new address firstname.lastname@example.org has received 105 different emails from 80+ different senders. Thank you for your help signing it up to email lists, and feel free to sign it up for more!
I tried to sign up some myself. I had trouble with a few attempts. Looks like you actually have to sign up for HBO or Showtime to get their emails (boo, no lead-gen?). And a handful of folks actually are utilizing double opt-in, which is great to see. Thanks, Cinemark, CBS News, Gear Wrench Tools, Aldi Austria (Hofer), Publix Grocery Stores, and Jersey Mike's Subs for actually verifying email addresses before assuming they're valid.
In case you're wondering, CBS News seems to use Mapp Digital (aka BlueHornet), NBC News seems to use Sailthru, and I have no idea what ABC News uses because they haven't sent any emails yet, even though the address is signed up.