At 02:51 -0400 on 04/06/2008, Hector Santos wrote about Re: How does
SMTP IPv4 and IPv6 work together:
> What justification do you offer to allow an IPv6 MTA to run without an
> EXPLICATE MX record?
I have started in my proposed in multiple messages and I repeated it
above what I believe is the practical solution here and minimal text for
2821bis without going overboard in trying something we are not sure
about yet - for new systems using new technology that WANT to continue
to operate and communicate in a IPv4, the MUST|SHOULD use a MX and/or
implicit MX A record in order to be compatible with current expectations.
My error in not stating my real question but assuming the caveat by
implication. To reword my query (*CAPS* are the omitted caveat):
What justification do you offer to allow an IPv6 MTA to run *VIA
IPv6* without an EXPLICATE MX record? IOW: If it is dual stack and
willing to use IPv4 then just allow the A-Fallback but why allow
AAAA-Fallback to allow it to talk via IPv6? Note: I was assuming that
an EXPLICATE MX would point not only to all the needed AAAA records
but also the A records that would be used by a IPv4-Only Stack in
Fallback mode (ie: Since the existence of the MX precludes A-Fallback
, the A records MUST be referenced by the MX).
I guess I will need to be more explicate in the future and avoid
unstated assumptions <g>.