That would be a seriously broken violation of the SMTP specification. I would definitely agree it would be quite broken behavior, but you know, I never said Hotmail's processing wasn't broken -- only that
On 7/27/12, Tony Finch <dot@dotat.at> wrote: they seem to honor MX records in the common case. If you are doing something unusual like "mail MX bla bla" I would say you can't rule that out as a possible cause, just because some RFC suggests it should be OK. The spec does say that you're not allowed to chain MX records. But i'm not so sure that the specification actually prohibits a SMTP server from doing that, if someone does try to chain MX records. it may also be out of spec to have a "MX" record point to a dns label that a MX record exists for in the first place.
Tony. -- f.anthony.n.finch <dot@dotat.at> http://dotat.at/ -- -JH