However, that is overly generous to IPv4 because a much higher percentage of the connections on IPv6 result in actual mail transfer while many of the IPv4 connections are various failed authentication attempts, attempts to deliver rejected (SPAM, other) messages, and other various failures to complete the delivery process (disconnects after EHLO, etc.).

As stated earlier, approximately 40% of all mail received by my MTA arrives over IPv6.

FWIW, most of my netflix viewing is done via IPv6 as well.

turning off IPv4 is a tall order and a huge risk for Netflix to take, so I don’t see that happening. You’re not wrong about the likely impact, but it would be a rough contest between ISPs telling their customers “Netflix turned us off, blame them” and Netflix telling its customers “We’re no longer supporting the legacy internet protocol and your ISP needs to modernize.”. In the end it likely turns into a pox on both their houses and the ISPs in question and Netflix both lose a bunch of customers in the process.

OTOH, as new products come out that are unable to get IPv4 and are delivered over IPv6 only, this will eventually have roughly the same effect without the avoidable business risk involved in Netflix leading the way. this is my primary argument against the proposal, it will further delay this inevitability which, in turn, prolongs the pain period of this transition. While a handful of new entrants might benefit in some way in the short term from such a thing, in the long term, it’s actually harmful to everyone overall.

Owen