Re: [ietf-smtp] Fwd: New Version Notification for draft-crocker-email-deliveredto-00.txt

[Alessandro Vesely <[e-mail]>]

On Fri 05/Feb/2021 15:53:16 +0100 Dave Crocker wrote:
> On 2/5/2021 2:56 AM, Alessandro Vesely wrote:
> 
>> 3) IDNs:
>>
>> When I write a message to user@foà.it (fake user, real domain) the MDA writes
>> Delivered-To: [e-mail].  I see no reason for doing so.  The message 
>> is SMTPUTF8 anyway because of the To: user@foà.it header field, which is 
>> maintained.  Are there reasons to mangle the domain name?
> 
> I'd guess that has more to do with software implementation that document 
> specification, but if there's a change to this spec you have in mind, please 
> offer it.


Meanwhile, I had asked the same question to the developer.  Here's what he 
answered:

     Until mail client are dominantly Unicode, one still needs to make allowance
     for ASCII mail clients that might balk on seeing 8-bit mail headers, hence
     the headers Courier adds will have UTF-8 domains translated to their ACE
     equivalents.

     Courier should accept UTF-8 userids. Can't do anything about that, so
     they'll still show up as UTF-8 in headers. This will require the IMAP or
     the POP3 client to enable Unicode support, else they'll get that warning.

I don't think that that text should go in the I-D.  However, if you can extract 
a savvy principle from it, it may be worth to add it to the spec...


Best
Ale
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