It appears that Jeremy Harris via Exim-users <jgh@???> said:
>On 11/29/23 15:51, John Levine via Exim-users wrote:
>> Strange but true, sending mail to this list via IPv6 does not work:
>>
>> 2023-11-29 10:35:50.715699500 new msg 271522
>> 2023-11-29 10:35:50.715750500 info msg 271522: bytes 2558 from <johnl@???> qp 83701 uid 82
>> 2023-11-29 10:35:50.726425500 starting delivery 466243: msg 271522 to remote exim-users@???
>> 2023-11-29 10:35:56.348847500 delivery 466243: failure:
>2a03:4000:0006:b381:0000:0000:0000:0002_does_not_like_recipient./Remote_host_said:_550_unknown_user/Giving_up_on_2a03:4000:0006:b381:0000:0000:0000:0002./STARTTLS_proto=TLSv1.3;_cipher=TLS_AES_256_GCM_SHA384;_subject=/CN=cumin.exim.org;_issuer=/C=US/O=Let's_Encrypt/CN=R3;/
>> 2023-11-29 10:35:56.376048500 end msg 271522
>
>Our log says that message was aimed at exim-users@???
Oh, I see the problem. lists.exim.org is a CNAME for cumin.exim.org,
and qmail is standard compliant per RFC 1123:
5.2.2 Canonicalization: RFC-821 Section 3.1
The domain names that a Sender-SMTP sends in MAIL and RCPT
commands MUST have been "canonicalized," i.e., they must be
fully-qualified principal names or domain literals, not
nicknames or domain abbreviations. A canonicalized name either
identifies a host directly or is an MX name; it cannot be a
CNAME.
When I put in an explicit route it uses that rather than resolving the CNAME,
unrelated to IPv6.
It's poor form to use a CNAME as a mail domain, and worse form not to
do what the standard says, but I suppose that horse left the barn a
long time ago.
R's,
John
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