Oh wow, TIL. Does that work? It says the draft expired in 2014. "[T]he SMTP client first looks up a DNS MX RR and if that is not found it falls back to looking

Oh wow, TIL. Does that work? It says the draft expired in 2014. "[T]he SMTP client first looks up a DNS MX RR and if that is not found it falls back to looking up a DNS A or AAAA RR. Many domains do not accept email, but do have A or AAAA records. If they have no MX records, senders will attempt to deliver mail to those A or AAAA records. " Nothing like a good opt-out to make you feel like you're signing up to a Do Not Call list. I guess we can't blame email too much, it's an incredibly old protocol. But at some point, some quirks have got to be worth rethinking, right? Maybe we can deprecate the fallback from MX to A/AAAA for the next, oh I don't know, two hundred years before we can move on.