[pfx] Re: SMTPUTF8

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.

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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