From: Daniel Kahn Gillmor <dkg@fifthhorseman.net>
To: David Bremner <david@tethera.net>, Gaudenz Steinlin <gaudenz@debian.org>,
 notmuch@notmuchmail.org, 810784@bugs.debian.org
Subject: Re: [Gaudenz Steinlin] Bug#810784: should match email adress case
 insensitive when sending encrypted mail
In-Reply-To: <87egdm4ujh.fsf@tesseract.cs.unb.ca>
References: <87egdm4ujh.fsf@tesseract.cs.unb.ca>
User-Agent: Notmuch/0.21+66~g8c19a9a (http://notmuchmail.org) Emacs/24.5.1
 (x86_64-pc-linux-gnu)
Date: Fri, 15 Jan 2016 13:47:51 -0500
Message-ID: <874mee7k88.fsf@alice.fifthhorseman.net>
MIME-Version: 1.0
Content-Type: text/plain
Precedence: list

On Tue 2016-01-12 11:44:18 -0500, David Bremner wrote:
> [gaudenz wrote:]
>>   When sending encrypted mail the key lookup to encrypt to is done case
>>   sensitive on the mail address. As mail addresses are case insensitive
>>   this should be done case insensitive. Otherwise keys for users which for
>>   some reason have uppercase letters in their email address in the key UID
>>   are not found.

fwiw, i agree with gaudenz that this is the right thing to do, despite
being a gray area.

For the right-hand side of an e-mail address (the stuff after the @; the
e-mail domain), the DNS label there is case-insensitive by definition.

There may be some additional thinking to be done here when thinking
about non-ASCII DNS labels in the RHS, though -- should we be
normalizing the domain names in doing the search?  using punycode?

The stuff before the @ is a bit more problematic.

According to the standards documents, the left-hand-side of an e-mail
address (the "domain-specific" part) is up to the mail domain to parse
and process.  So it would not be a violation of the public
specifications for the operator of the MX for example.org to provide
three distinct mailboxes for alice@example.org and Alice@example.org and
ALICE@example.org.

However, i know of no mail providers that do so, and anyone proposing to
do such a thing should have their head examined.

Examining GnuPG's interface here, it looks like gpg already does
case-insensitive matching when searching for an e-mail address
surrounded by angle-brackets.

So where is the case-insensitive lookup happening?  Is this a bug in
mml-mode, or in notmuch-emacs?

          --dkg