In message <537d9d47.3000...@necom830.hpcl.titech.ac.jp>, Masataka Ohta writes: > (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 ...
Why are you complaining about this? Do you have a time machine to correct it? The prohibition has been removed but we still need to be aware that it existed, that there are MUA that still re-write based on the CNAME and it impacts on the solution space. Just use CNAME has negative consequences. > 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 -- Mark Andrews, ISC 1 Seymour St., Dundas Valley, NSW 2117, Australia PHONE: +61 2 9871 4742 INTERNET: ma...@isc.org _______________________________________________ DNSOP mailing list DNSOP@ietf.org https://www.ietf.org/mailman/listinfo/dnsop
