Slightly OT - MX RR Santity Check requested...
Mark Andrews
Mark_Andrews at isc.org
Thu Mar 29 02:30:11 UTC 2007
>
> > In article <euf4o6$98o$1 at sf1.isc.org>,
> > Mark Andrews <Mark_Andrews at isc.org> wrote:
> >
> > > > You mean "their" configuration is broken? The sending mail server is N
> OT
> >
> > > > ours. We're on the receiving end.
> > >
> > >
> > > No. Your configuration is broken. The lowest preference
> > > MXs MUST always be reachable. You cannot depend upon
> > > fallback to higher preference MXs. The sending side is not
> > > required to try them. It is required to try all the lowest
> > > preference MXs.
> >
> > RFC 2821 seems to contradict you:
> >
> > When the lookup succeeds, the mapping can result in a list of
> > alternative delivery addresses rather than a single address, because
> > of multiple MX records, multihoming, or both. To provide reliable
> > mail transmission, the SMTP client MUST be able to try (and retry)
> > each of the relevant addresses in this list in order, until a
> > delivery attempt succeeds. However, there MAY also be a configurable
> > limit on the number of alternate addresses that can be tried. In any
> > case, the SMTP client SHOULD try at least two addresses.
>
> This does not cover how the list of addresses is choosen.
> RFC 952 still applies. The list of addresses can legally
> be those of just the lowest preference MXs.
Opps. RFC 974
> > --
> > Barry Margolin, barmar at alum.mit.edu
> > Arlington, MA
> > *** PLEASE post questions in newsgroups, not directly to me ***
> > *** PLEASE don't copy me on replies, I'll read them in the group ***
> >
> >
> --
> Mark Andrews, ISC
> 1 Seymour St., Dundas Valley, NSW 2117, Australia
> PHONE: +61 2 9871 4742 INTERNET: Mark_Andrews at isc.org
--
Mark Andrews, ISC
1 Seymour St., Dundas Valley, NSW 2117, Australia
PHONE: +61 2 9871 4742 INTERNET: Mark_Andrews at isc.org
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