Victor, --On Saturday, June 29, 2024 19:38 +1000 Viktor Dukhovni <ietf-dane@xxxxxxxxxxxx> wrote: > On Sat, Jun 29, 2024 at 12:00:43AM -0400, John C Klensin wrote: > >> > For context, absolutely none of the major email delivery >> > providers (AWS SES, SendGrid, Mailgun, Postmark, SMTP_com, etc.) >> > support ipv6. ... First, to keep _that_ in context, it was Nicolas's comment, not mine. > That of course has nothing to do with SMTP (the protocol) as such. > There are a few plausible tangential reasons: > > - Some receiving systems are more strict in what they're willing > to accept via IPv6 rather than IPv4. As a consequence, one > can choose to try to jump through more hoops, or just be sure > to send via IPv4. [ The extra scrutiny may be because with > so much address space in IPv6, IP reputation is perhaps less > effective, without additional signals. ] > > - IPv4 works well enough that the incentives aren't there to > invest scarce human cyles into bringing up outbound services > on IPv6. I would have added an explicit comment about perceived economics and profitability, but your second comment almost implies that. > Meanwhile, major MTAs have had mature IPv6 support too long go to > remember [ O.K. ~20 years in the case of Postfix. ] And that, as well as the state of the protocol specs, was what prompted me to ask Nicolas what specific problems/issues he was seeing. > The issues are non-technical at this point, some major receiving > systems need to make it more (rather than less) attractive to send > over IPv6. Complete agreement. But it seems to me that takes us back to much of the original thread, including comments about dog food-eating. My version would be something like: The IETF does not support email over IPv6 for perfectly reasonable and pragmatic reasons which have nothing to do with deficiencies in the protocols themselves. However, unless we are happy with others drawing the inference that we do not believe IPv6 support (or IPv6 itself) is relevant and important, we have some obligation to either support it or provide a public explanation of why not. I think that explanation might be part of the various listing of mailing lists and/or the subscription boilerplate. We might ask vendors why they do not have an email-over-IPv6 option and include the response and/or indicate that we are tracking the situation and will make email-over-IPv6 available as soon as it is practical. >From my point of view, this is mostly about the IETF's credibility when we establish standards and at least implicitly encourage others to use them. If we do not or cannot use those standards in our own work, and avoid doing so without public and understandable explanations, it calls everything we are doing into question. john
