Dave T?ht:
> wie...@porcupine.org (Wietse Venema) writes:
>
> > Dave Taht:
> >> So what I think I want to do is setup fallback relaying as follows:
> >>
> >> MX 5 mylaptop.example.org # if my laptop's up send mail there
> >> MX 10 mytinyarmbox.example.org # if not, try my arm box
> >> MX 20 mysmarthost.example.org # otherwise, default to my well connected
> >> host
> > ...
> >> Problem 1) I am under the impression from a foggy memory of reading some
> >> RFC or other, that at minimum, 2 MX records will be tried. So adding a
> >> third might introduce problems with some MTAs that ONLY do 2 MX records,
> >> in that far off day when more stuff speaks ipv6 directly, or when it
> >> fails to fallback to my third, primary smarthost.
> >
> > SMTP is defined in RFCs and the ones concerning SMTP are RFC 821,
> > RFC 2821, and RFC 5321. By now, most mail systems in existence will
> > be build after RFC 2821, which says "the SMTP client SHOULD try at
> > least two addresses". With three MX hosts you're operating outside
> > the recommendation.
>
> Many hosts seem to have more than 2 MX records. Gmail, for example,
Unlike your unsupported configuration, gmail etc. do NOT require
that a client tries MORE THAN TWO addresses.
Wietse
