SM wrote:
Hi Paul,
At 02:39 31-03-2008, Paul Smith wrote:
Either:
- toaster.example.org is going to send a message with the return-path
of [EMAIL PROTECTED], in which case I'd EXPECT
toaster.example.org to have an SMTP server running on it, hence an MX
record would not be a bad thing, or
- toaster.example.org is going to send a message with a null return
path, in which case what does it matter..
The discussion have been whether the receiver should explicitly specify
a MX RR to determine whether it accepts mail. If we stretch the MX RR
requirement to a forward and reverse model, then the sender
(toaster.example.org) also has to have a MX RR. This means that the
change affects both senders and receivers. If we use a null
return-path, the sender won't know whether there was a delivery failure.
<snip>
I think that stretching the MX RR requirement to both a forward and
reverse model is not something we should necessarily consider. I
believe that would change the architecture too fundamentally.
I do stand on the side that MX records should be required for IPv6 only
hosts that wish to receive mail at a FQDN.
The reason this must be discussed now, is because if 2821bis is
published allowing AAAA fall-back, then we can never* change it in the
future.
- Willie
* Obviously by never, I mean that it wouldn't ever happen. That that it
theoretically couldn't happen.
