SMTP predates the "MX" rrtype. In RFC821, "c...@stdlib.net" means "connect to the host stdlib.net" and host records (e.g. "A" and now "AAAA") are what matters [*]. RFC1123 and later RFC2821 regularised the "MX" rrtype for mail routing, obviating the need for the host records at a mail domain.
However, the correct SMTP behavior, at least considered by many, still is that if you don't find an MX record for a domain name, try to find a host record. From the point of view of an SMTP server, an "ANY" query is a rational way to find all of the records it will need, in one pass. [*] Well at various times, MD, MF, MAILA and MAILB were all relevant too, but those have fallen completely out of disuse. On Sun, Jun 10, 2012 at 3:17 AM, Dobbins, Roland <rdobb...@arbor.net> wrote: > > Clue appreciated, thanks! > > ----------------------------------------------------------------------- > Roland Dobbins <rdobb...@arbor.net> // <http://www.arbornetworks.com> > > Luck is the residue of opportunity and design. > > -- John Milton > > _______________________________________________ > dns-operations mailing list > dns-operations@lists.dns-oarc.net > https://lists.dns-oarc.net/mailman/listinfo/dns-operations > dns-jobs mailing list > https://lists.dns-oarc.net/mailman/listinfo/dns-jobs -- Colm _______________________________________________ dns-operations mailing list dns-operations@lists.dns-oarc.net https://lists.dns-oarc.net/mailman/listinfo/dns-operations dns-jobs mailing list https://lists.dns-oarc.net/mailman/listinfo/dns-jobs