The technical side of this seems easy enough. The human side, that seems more complicated.
Like, if I were your doctor or contractor or kid's schoolteacher or whoever you hadn't happened to already whitelist, and had sent you something important for you, and got that back as a response... I'm sure as heck not paying when I'm trying to send you something for your benefit.
It's a great way to stop receiving anything that benefits yourself and only start receiving mail which could make the sender way more than $1