Re: [dane] email canonicalization for SMIMEA owner names

"John Levine" <johnl@taugh.com> Thu, 11 December 2014 22:51 UTC

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Date: Thu, 11 Dec 2014 22:50:38 -0000
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From: John Levine <johnl@taugh.com>
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Subject: Re: [dane] email canonicalization for SMIMEA owner names
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>So I thought about punycode RFC3492. I know the RFC might only be for domains, but I asked
>myself, why this would not be applied to a local part as well.

Mailboxes can contain characters not valid in punycode.  Mailboxes in
regular ASCII mail can contain spaces and ASCII graphics.  Mailboxes
in EAI mail can include arbitrary UTF-8.

You could imagine a punycode-like encoding for mailboxes, or perhaps
something more like quoted printable, but punycode or A-labels aren't
adequate.

Also keep in mind that RFC 5321 says that mailbox names are opaque, so
any case folding we do is technically wrong.  But in practice everyone
expects case folded mailboxes to work, so even mail purists are likely
to grumble but admit that a hack like Viktor's optional lower case is
OK.

R's, John