--On Friday, June 28, 2024 19:52 -0400 Nicolas Giard <nick@xxxxxxxxxxxxxx> wrote: > For context, absolutely none of the major email delivery providers > (AWS SES, SendGrid, Mailgun, Postmark, SMTP_com, etc.) support ipv6. >... > The email world is unfortunately still overwhelmingly ipv4 and > unlike other protocols, adding ipv6 support is not trivial. >... Nicolas, Because of a probably relevant document I'm working on in/for the IETF [1] and my roles with several of its predecessors, the portion of the above statement starting with "unlike other protocols..." strikes me as a bit strange. SMTP started out as a protocol running over NCP and was migrated to TCP / IPv4 with relatively little pain. That implies some cleanliness of design. My understanding has been that several SMTP MTAs have been adjusted to support IPv6 and that the most important problem since mechanisms for use with IPv6 were specified in RFC 2821 (in April 2001) has involved keeping up with subtle changes in the preferred presentation form of IPv6 address literals. The mail format specification (RFC 5322) is even less sensitive to details of the underlying transport. So, could you explain what you believe makes it more difficult to add IPv6 support to email than "other protocols"? Now, if instead of saying "email" you has said something about two-way IPv4 <-> IPv6 email gateways or issues with mail submission systems or MUAs that are implemented in ways that are inconsistent with the spirit and intent of the standards, that might be a different story entirely. But, if you see problems with the core email protocols and IPv6, I, and presumably the EMAILCORE WG would like to know about them... and soon. thanks, john [1] draft-ietf-emailcore-rfc5321bis
