Subject: [EAI] Partly internationalised mail

From: Arnt Gulbrandsen <[email-masked]>
Date: Tue, 10 Sep 2013 19:17:50 +0200

Hi,

consider the following field:

To: Æ <[email-masked]>, Å <[email-masked]>

That is indubitably a valid EAI field. But then consider:

To: Æ <[email-masked]>, =?q?iso-8859-1?FF=? <[email-masked]>

I can't remember the 2047 rules, despite having implemented them
twice. But you get the point. That is, as far as I can see, valid.

Perhaps somewhat surprising. I did not expect that my code would use
both UTF-8-EAI-ish syntax and 2047 syntax in the same field. But it
seems valid, and the code is the most straightforward implementation
was the simplest design.

Arnt

---

From: John C Klensin <[email-masked]>
Date: Tue, 10 Sep 2013 14:02:16 -0400

--On Tuesday, September 10, 2013 19:17 +0200 Arnt Gulbrandsen
<[email-masked]> wrote:

> I can't remember the 2047 rules, despite having implemented
> them twice. But you get the point. That is, as far as I can
> see, valid.

Valid but in bad taste.  EAI discourages any use of encoded
words in headers in favor of decoding them into UTF-8.  I can't
remember if it actually says "SHOULD NOT" do the above, but,
again, the intent was to discourage and get rid of that usage
(and, in the process, of non-Unicode creatures like 8859-1).

> Perhaps somewhat surprising. I did not expect that my code
> would use both UTF-8-EAI-ish syntax and 2047 syntax in the
> same field. But it seems valid, and the code is the most
> straightforward implementation was the simplest design.

It is hard or impossible to prohibit encoded words entirely
because one can't compel the EAI client MUA to have decoders for
every charset that might appear in such a thing (especially
From: header fields and To: header fields generated by replies.
Suppose you receive something containing 

   From: =?q?johns-made-up-charset?FF00FF=?
<[email-masked]>

The sender would clearly have been bad by not registering it
with IANA and you have no hope of decoding it into Unicode.
You could give it a high "sender-is-probably-an-idiot" score
and, if you believe that most spammers are idiots and that most
idiots are also spammers, maybe a high "probably-spam" score.
But you probably aren't going to reject it so, when the user
tries to reply...  

>From a protocol point of view, that is just another reason to
encourage on-the-wire use of nothing but UTF-8 these days and
for discouraging use of encoded words, even encoded UTF-8.
But...

    john

---

From: "Jiankang Yao" <[email-masked]>
Date: Wed, 11 Sep 2013 16:03:13 +0800

I have seen some similar implemenation example in the current implementation.

Jiankang Yao

From: Arnt Gulbrandsen
Date: 2013-09-11 01:17
To: ima
Subject: [EAI] Partly internationalised mail
Hi,

Arnt
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