Re: [ietf-smtp] Should we update an RFC if people refuse to implement parts of it ?

Alessandro Vesely <vesely@tana.it> Tue, 01 June 2021 17:32 UTC

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From: Alessandro Vesely <vesely@tana.it>
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Subject: Re: [ietf-smtp] Should we update an RFC if people refuse to implement parts of it ?
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On Tue 01/Jun/2021 02:54:32 +0200 Ned Freed wrote:
> 
> To the extent Received: fields are relevant to our customers, it's to track down
> the cause of some sort of problem, usually but not always some kind of delivery
> delay. I find A-label better suited to this usage than U-labels.


Nowadays, Received: fields are often intermixed with Authentication-Results:, especially near the top of the header.  The latter provides U-Labels, AFAICS.  That way, both kinds of labels are available.  Here's a couple of examples:

By Courier-MTA:

Return-Path: <postmaster@xn--fo-kia.it>
Authentication-Results: wmail.tana.it;
   spf=pass smtp.mailfrom=foà.it;
   dkim=pass (whitelisted) header.d=foà.it
Received: from xn--fo-kia.it (wmail.tana.it [62.94.243.226])
   by wmail.tana.it with ESMTP
   id 00000000005DC026.0000000060B66AC3.00007C42; Tue, 01 Jun 2021 19:13:02 +0200


By Google:

Authentication-Results: mx.google.com;
        dkim=pass header.i=@foà.it header.s=gamma header.b=BHORghd0;
        spf=pass (google.com: domain of postmaster@foà.it designates 62.94.243.226 as permitted sender) smtp.mailfrom=postmaster@foà.it;
        dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=xn--fo-kia.it


Still, Section 3.7.3 of RFC 6531 doesn't seem to say that A-R's are trace fields...


>> On the other hand, and here comes the question: There are proposals
>> floating around that would define new header fields that would
>> reflect, include, or depend on, different sorts of forward-pointing
>> and reverse-pointing addresses.  Should we be taking the position
>> that none of those should move forward unless they explicitly
>> address what should be done when those fields are not traditional
>> ASCII ones?> 
> Very good point. EAI is a standards-track format/protocol. An unavoidable
> consequence of this is that proposal that involves a new header field needs to
> say how it interacts with EAI, even if it's only to say it doesn't interact at
> all.


If not specified, it looks like Section 3.6 of RFC 6532 supplies a default:

    encoded-words SHOULD NOT be used when generating header fields for
    messages employing this extension.  Agents MAY, when incorporating
    material from another message, convert encoded-word use to direct use
    of UTF-8.


Best
Ale
--