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Re: [dane] case sensitivity and draft-ietf-dane-smime / draft-wouters-dane-openpgp

Viktor Dukhovni <viktor1dane@dukhovni.org> Mon, 09 September 2013 15:33 UTC

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From: Viktor Dukhovni <viktor1dane@dukhovni.org>
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Subject: Re: [dane] case sensitivity and draft-ietf-dane-smime / draft-wouters-dane-openpgp
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On Mon, Sep 09, 2013 at 10:52:26AM -0400, Paul Wouters wrote:

> Mail servers and mail clients do not treat email addresses as
> case-insensitive. When encoding an LHS with base32, the case matters.
> Using the wrong case will cause you to not find the SMIMEA / OPENPGPKEY
> record.

This is not accurate.  While domain part of an email address is
case-insensitive, the case-sensitivity of the local-part  is a
local matter.  SMTP relays MUST NOT change the case of the local
part of envelope addresses.  On arrival at the destination domain,
that domain's mail system may choose to treat local-parts case
insensitively, but remote systems must not rely on this.

Therefore, <Paul@example.com> and <paul@example.com> are a-priori
distinct addresses except perhaps in the hands of the MTAs that
handle example.com mail.

[ The fact that most systems are in practice case-insensitive is not
  sufficient to invalidate the right of some to be case sensitive as
  they see fit. ]

-- 
	Viktor.

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