BTW, John mentioned upthread that sending mail via IPv6 was accidentally disabled a while back.
I'm puzzled. I have verified that mail from an Office365 user to a Gmail user is IPv6 all the way, including:
Received: from AUS01-SY4-obe.outbound.protection.outlook.com (mail-sy4aus01on20700.outbound.protection.outlook.com. [2a01:111:f403:201e::700])
by mx.google.com with ESMTPS id 41be03b00d2f7-7481f5d1a9asi596453a12.809.2024.06.30.15.06.36
for <brian.e.carpenter@xxxxxxxxx>
(version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128);
Sun, 30 Jun 2024 15:06:36 -0700 (PDT)
which demonstrates that Gmail happily accepts incoming SMTP/IPv6. (The converse isn't true - SMTP from Gmail to Office365 travels via IPv4.)
However, when I look at an IETF message from about a year ago, I see:
Received: from mail.ietf.org (mail.ietf.org. [50.223.129.194])
by mx.google.com with ESMTPS id w10-20020a17090aad4a00b00259a3c7fb52si2700554pjv.27.2023.07.21.00.35.45
(version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256);
Fri, 21 Jul 2023 00:36:03 -0700 (PDT)
So if the IETF was willing to send SMTP/IPv6 then, Gmail wasn't playing. Does anybody have evidence that it actually worked?
Regards
Brian
