Re: Last Call: draft-klensin-rfc2821bis

Ned Freed wrote:

> If the consensus is that better interoperability can be had
> by banning bare AAAA records that's perfectly fine with me.

FWIW, I'd like that...

>> Clarity can be established and interoperability _improved_ 
>> by limiting discovery to just A and MX records.  Perhaps a
>> note might be included that at some point in the future MX
>> records may become required.

> Again, I have no problem with this approach if that's what
> the consensus is.

...and that, too.  

>> Adding AAAA and all future address records to a list of 
>> SMTP discovery records fails miserably at taking advantage
>> of the MX record replacing the function of the generic A
>> record.

> Another point in favor of not allowing bare AAAA records
> for mail routing.
[...]
>> The only valid solution would be to indicate that AAAA 
>> records as a discovery mechanism may not be supported and
>> should not be used for this purpose.  Use MX records instead.

> Which is perfectly fine as far as I'm concerned. The question
> is whether there's a consensus to resolve the ambiguity in
> this fashion.

Checking about 63 articles on the SMTP list mentioning "AAAA",
some from the early '90s, they're about TLDs, CNAME, MX, SPF,
and what else.  I found no message clearly saying "but I want
no MX for my AAAA".  I vaguely recall that somebody mentioned
an implementation doing this, but that is not the same as "I
insist on an AAAA fallback", and IIRC it was only one poster.

 Frank

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