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

Ned Freed <> Sun, 30 May 2021 23:31 UTC

Return-Path: <>
Received: from localhost (localhost []) by (Postfix) with ESMTP id 187D43A1939 for <>; Sun, 30 May 2021 16:31:44 -0700 (PDT)
X-Virus-Scanned: amavisd-new at
X-Spam-Flag: NO
X-Spam-Score: -2.1
X-Spam-Status: No, score=-2.1 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, SPF_PASS=-0.001, URIBL_BLOCKED=0.001] autolearn=ham autolearn_force=no
Authentication-Results: (amavisd-new); dkim=pass (1024-bit key)
Received: from ([]) by localhost ( []) (amavisd-new, port 10024) with ESMTP id ZlhTFCHWbT_H for <>; Sun, 30 May 2021 16:31:38 -0700 (PDT)
Received: from ( []) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by (Postfix) with ESMTPS id E1A313A1936 for <>; Sun, 30 May 2021 16:31:38 -0700 (PDT)
Received: from by (PMDF V6.1-1 #35243) id <> for; Sun, 30 May 2021 16:26:35 -0700 (PDT)
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed;; s=201712; t=1622417195; bh=hLV8eVS8Civf/E4GvWEvAcN17EHkvVeVJBQpOEkAMcE=; h=Cc:Date:From:Subject:In-reply-to:References:To:From; b=aVjO8sMH0iqXtwZPjg2Z/tQhv/0KQ4u8+bQMdqRqwrEUfZTuLTn3Bj8RcC712ZuFH yOFOhuqNJcGQsgMgJ6XQjJtq0X3oXgzMSntJ/Xj+VlPBCWfzR7piem3edrTsJUg8OG Sov9cNELpnJLfyFqUqVJ0c7foTcHOrntxXwanjzg=
MIME-version: 1.0
Content-transfer-encoding: 7BIT
Content-type: TEXT/PLAIN; CHARSET=us-ascii
Received: from by (PMDF V6.1-1 #35243) id <>; Sun, 30 May 2021 16:26:32 -0700 (PDT)
Message-id: <>
Date: Sun, 30 May 2021 15:49:25 -0700 (PDT)
From: Ned Freed <>
In-reply-to: "Your message dated Wed, 26 May 2021 17:59:49 -0400" <>
References: <20210525182946.079748B872C@ary.qy> <EFDA46E00EFF0E48802D046A@PSB> <> <>
To: Viktor Dukhovni <>
Archived-At: <>
Subject: Re: [ietf-smtp] Should we update an RFC if people refuse to implement parts of it ?
X-Mailman-Version: 2.1.29
Precedence: list
List-Id: "Discussion of issues related to Simple Mail Transfer Protocol \(SMTP\) \[RFC 821, RFC 2821, RFC 5321\]" <>
List-Unsubscribe: <>, <>
List-Archive: <>
List-Post: <>
List-Help: <>
List-Subscribe: <>, <>
X-List-Received-Date: Sun, 30 May 2021 23:31:44 -0000

> On Thu, May 27, 2021 at 12:59:53AM +0800, Jiankang Yao wrote:

> > > I recognize the distinction while also realizing that, as you know,
> > > things often leak.  My recollection (if Jiankang is following this,
> > > his memory is probably better than mine) is that the WG explicitly
> > > discussed the issue and concluded that U-labels were a better idea
> > > than A-labels.
> >
> > Yes, I think so. The EAI WG discussed this issue.  Section 3.7.3.
> > Trace Information  encourages to use UTF-8 form.  One reason I think
> > is that trace information will be put into header for human reading.

> But, and this is crucial, the human reading the trace information is
> rarely either the sender or the ultimate recipient of the message, who
> are generally presented with a subset of the headers fields ("To", "Cc",
> "Date", "Subject" ...).  Examination of trace headers is far more likely
> to a task for a mail system administrator.  They're used in abuse
> reports and the like, and a uniform representation is more important
> than familiarity to the community of readers of some given language.

And what the admin usually wants to do is either a comparison or check the
domain with the DNS in some way. So an A-label can be more convenient.

And in the unlikely event an admin needs to translate the A-label to a
U-label, there are an abundance of tools that I can use to do it.

> Mail system administrators don't necessarily read the same scripts as
> their end users.  Mail system administrators would reasonably expect
> the EHLO name recorded in trace headers to match the name received in
> the actual EHLO command on the wire (and recorded in their email logs).

> > UTF-8 is better for human reading.  A-label is ugly for human reading,
> > but ok for machine reading.

> Sure, if the text is Russian, some Latin-based alphabet or at a stretch
> Greek, I can more easily distinguish one U-label string from another
> than an A-label form like "", ... and yet I'd much
> rather see A-labels in trace headers than Arabic or Chinese.  The text
> in 3.7.3 is not something I'm inclined to implement.

Actually, it depends on the A-labels. Because of the compression involved
A-labels often emphasize small differences that may be difficult to see in a
crap monospaced font for a non-Latin script, even one you're familiar with.

> Specifying the use of U-labels in the "from" and "by" clauses rather
> looks like a bad judgement call, rough consensus or not.  Until the
> Protocol Police show up, I'm sticking with A-labels. :-(

Me too.