(2014/05/22 14:00), S Moonesamy wrote:
> Hi John,
> At 10:43 21-05-2014, John Levine wrote:
>> See RFC 1123, section 5.2.2.
>
> Tony Finch already commented about RFC 1123. That section has been
> replaced (see RFC 5321). Section 8.7 of RFC 6409 is applicable for mail
> submission and CNAME.
What rfc1123 prohibit with no good reason is using
"f...@bar.example.com" as a mail address in MAIL and RCPT, when:
bar.example.com CNAME mail.example.com
mail.example.com MX ...
even though it is a valid configuration explicitly admitted in rfc974,
whereas rfc974 mentions (and rfc5321 forbids):
cname.example.com CNAME mx.example.com
mail.example.com MX 0 cname.example.com
MX 1 other.example.com
MX 2 mx.example.com
may cause a mail loop, if mx.example.com receives mail to
mail.example.com MX 0 cname.example.com
misunderstanding that they are to
MX 2 mx.example.com
It is not a problem if mail software properly recognize host
identity including aliases.
Masataka Ohta
_______________________________________________
DNSOP mailing list
DNSOP@ietf.org
https://www.ietf.org/mailman/listinfo/dnsop
