[pfx] Re: SMTPUTF8

On 03-07-2026 03:04, John R. Levine wrote:
> On Thu, 2 Jul 2026, Danjel Jungersen wrote:
>>> That's an Internationalized Domain Name (IDN), in the Unicode 
>>> U-label form.
>>> THe encoded A-label equivalent which you can look up in the DNS is 
>>> xn--vestskovslbet-knb.dk
>>> ...
>>> A possible workaround is to send mail to the A-label version of the
>>> address, [email protected] which would not need SMTPUTF8.
>>> I poked at the server and it accepted that address.
>>
>> Is there a reason why this is not attempted automatically?
>
> Postfix considers the A-label and U-label versions of the address to 
> be distinct.  Wietse might tell us what the thinking was.
>
>> The receiver claims that he receives mail from other people using the 
>> IDN version.
>
> Honestly, I'm sceptical.  My guess is that the other people have the 
> A-label version of the address in their address book, and his mail 
> program doesn't show him the address in incoming mail.
>
Thank you all for your time.

Just a little update.

The receiver still claims "that it works".
But the receiver is a volunteer in a project / event.
The project is now cancelled, they did not get enough responses for 
extra hands to help with the event.

So maybe I'm just the only one asking questions...

JM2C

Danjel




> I have done a lot of EAI related work for ICANN and I can tell you 
> that using IDN mail addresses is one of those things that is supposed 
> to work but is painful in practice.  A lot of software almost but not 
> quite implements it, as we saw here.  Postfix support is fine (one of 
> the things I did was to test it and it got a gold star) but you have 
> to turn it on.
>
> R's,
> John


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