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 "xn--b1adqpd3ao5c.org", ... 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.
Ned
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