On Tue, Sep 10, 2002 at 08:59:00AM +0200, Kai Henningsen wrote:
> torvalds@transmeta.com (Linus Torvalds) wrote on 09.09.02 in <Pine.LNX.4.44.0209090831240.1641-100000@home.transmeta.com>:
> > where "reload.namesys.com" is not in the MX domain:
> >
> > dig -t MX reload.namesys.com
> ... i.e., does not have a MX record.
> > (Yes, I realize that both addresses likely work perfectly fine, and that
>
> Since the RFCs *demand* that an address mentioned in mail has an MX
> record, and the fallback to A records was not, until recently, described,
> there probably are some mailers that cannot deliver mail to that address.
> Which, in my book, counts as "not perfectly fine", even though I admit
> those mailers are probably in a minority as, sadly, this particular
> disease is pretty widespread.
You haven't read your RFCs. They demand no such thing!
Recently the compilations of RFC 2821 and 2822 were done because there
are about a dozen RFCs full of obscure details, and even errors.
RFC 1123 (Requirements for Internet Hosts -- Application and Support)
does say that the SMTP CLIENT (e.g. sending SMTP system) must support
and use MXes. RFC 974 says HOW:
RFC 974 around page 4: (Mail Routing and the Domain System)
Interpreting the List of MX RRs
....
It is possible that the list of MXs in the response to the query will
be empty. This is a special case. If the list is empty, mailers
should treat it as if it contained one RR, an MX RR with a preference
value of 0, and a host name of REMOTE. (I.e., REMOTE is its only
MX). In addition, the mailer should do no further processing on the
list, but should attempt to deliver the message to REMOTE. The idea
here is that if a domain fails to advertise any information about a
particular name we will give it the benefit of the doubt and attempt
delivery.
...
> MfG Kai
/Matti Aarnio
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This archive was generated by hypermail 2b29 : Sun Sep 15 2002 - 22:00:20 EST