--On Samstag, September 04, 2004 02:26:39 +0200 Alex van den Bogaerdt
<alex(_at_)ergens(_dot_)op(_dot_)het(_dot_)net> wrote:
On Fri, Sep 03, 2004 at 02:51:54PM -0400, David Brodbeck wrote:
On Fri, 3 Sep 2004 19:48:15 +0200, jpinkerton wrote
> MX records are not required. I remember reading somewhere - possibly
> even on this list - about exactly that. Try setting up a domain
> without one and then use the mail :-)
Right, if there's no MX record the MTA is supposed to fall back to
looking for an A record. In fact, until a couple weeks ago the domain
I'm sending from right now had no MX record, mostly due to laziness on
my part.
An MX record is just a way to say "do not deliver directly to this host,
use that other host instead".
So, instead of saying "fall back to the A record", IMHO you should think
of it as "there's no MX record overriding the A record".
No, RFC2821 is quite specific about this (as RFC974 was before that):
If no MX records are found, but an A RR is found, the A RR is treated as
if it was associated with an implicit MX RR, with a preference of 0,
pointing to that host.
This means definitely "fall back to A if no MX is present" and not the
other way around.
Ralf Döblitz