Re: Last Call: draft-klensin-rfc2821bis

On Wed, Mar 26, 2008 at 12:10:38AM -0700, SM wrote:
> At 19:32 25-03-2008, Bill Manning wrote:
> >         er...  what about zones w/ A & AAAA rr's and no MX's?
> >         when I pull the A rr's, you are telling me that SMTP
> >         stops working?  That is so broken.
> 
> SMTP will still work as the above case is covered by the implicit MX rule.

	presuming the existance of an MX...  (thats the "implicit"
	part of the "rule").

> The implicit MX rule creates an ambiguity during the transition from 
> IPv4 to IPv6.  That's discussed in Section 5.2 of the draft:
> 
>    "The appropriate actions to be taken will either depend on local
>     circumstances, such as performance of the relevant networks and any
>     conversions that might be necessary, or will be obvious
>     (e.g., an IPv6-only client need not attempt to look up
>     A RRs or attempt to reach IPv4-only servers). Designers of
>     SMTP implementations that might run in IPv6 or dual stack
>     environments should study the procedures above, especially the
>     comments about multihomed hosts, and, preferably, provide mechanisms
>     to facilitate operational tuning and mail interoperability between
>     IPv4 and IPv6 systems while considering local circumstances."
>

	what this daft is trying to do is force the presumptive
	existance of an MX in a zone into an explict rule that 
	forces the existance of an MX, else SMTP fails.

> We could look at the question by asking whether the fallback MX 
> behavior should be an operational decision.  But then we would be 
> treating IPv4 and IPv6 differently.

	IPv4 and IPv6 are different.

--bill

> 
> Regards,
> -sm 
> 
> _______________________________________________
> IETF mailing list
> IETF@ietf.org
> https://www.ietf.org/mailman/listinfo/ietf

-- 
--bill

Opinions expressed may not even be mine by the time you read them, and
certainly don't reflect those of any other entity (legal or otherwise).

_______________________________________________
IETF mailing list
IETF@ietf.org
https://www.ietf.org/mailman/listinfo/ietf