[idn] A UTF-8 test for mail clients

["D. J. Bernstein" <djb@cr.yp.to>]

[The first version of this message was corrupted by the mailing-list
manager. The From line wasn't an approved submitter, so the message was
put on hold pending approval; the approval mechanism generated a new
header, omitting the relevant MIME header fields.]


1. This is a MIME message with charset=utf-8. Your mail client should
display the two-byte UTF-8 sequence \317\200 in the message body as the
Greek letter pi. Here's a pi between brackets: [π]


2. This message also includes a pi in the Reply-To line, right before
the @:

   Reply-To: "D. J. Bernstein" <djb-pibounce-π@cr.yp.to>

Of course, there's no character-set declaration for that address, but
your client should display it as UTF-8 anyway. The most common mistake
will be to treat it as 8859-1: a double-dotted I and a block.


3. Try replying to this message. Your mail client and mail server should
be able to handle the djb-pibounce-π@cr.yp.to address. You will receive
a bounce from muncher.math.uic.edu showing the exact contents of your
mail as received by my mail server.

Note that there's no IDN here. The non-ASCII characters in the address
are in the box part, not the domain part. But that difference doesn't
matter for typical mail clients. This test avoids triggering DNS client
bugs, such as the BIND gethostbyname() bug.

The address will be corrupted if your message passes through Sendmail:
the second pi byte, \200, will be stripped. You will still receive a
bounce from muncher in this case.

Finally, send a message to results@pi.cr.yp.to telling me what happened.

---Dan