Re: [Emailcore] Ticket #50: Use of top level domains in SMTP

[John C Klensin <[e-mail]>]

--On Friday, July 23, 2021 07:52 -0700 Dave Crocker
<[e-mail]> wrote:

> On 7/23/2021 7:38 AM, Alexey Melnikov wrote:
>> I believe there was rough agreement in the past that use of
>> top level  domains is going to cause interop problems, as
>> depending on context they  might not be distinguishable from
>> local hostnames. If people agree, I  think the Applicability
>> Statement draft should talk briefly about this.

> Yes, as long as the language makes clear that the conflict is
> between an enhanced, standardized bit of functionality, with
> local, non-standardized functionality.

Dave,

I think I agree, but I'm not certain what you have in mind.
Could you, or someone else, elaborate a bit?

On a possibly-related topic, the DNSOP WG is considering
proposals to officially allow private-use strings as top level
domains.  If those proposals are approved, is it necessary to
add language to either the discussion of FQDNs in RFC5321bis
(noting that ticket #41 has been closed) or to add language to
the A/S to be clear that MTAs are expected to not let such
things escape onto the public Internet, just as they are
expected to prevent such addresses as example@local and
[e-mail] from escaping.

   best,
     john