Converting email addresses between Unicode and ASCII is non
trivial, as three different encodings are used (RFC2047, IDNA and
ASCII). Here is an EmailAddress I use and a test suite, which I feel
should be integrated into the email package. I'm quite happy to
implement a different interface if the 'unicode subclass' design is
unsuitable, although I got no feedback from the Email-SIG so they
are either happy with it or asleep ;)

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I think it is inappropriate to create new API for this.
Instead, one of the many functions that already deal with
address parsing need to be enhanced. For example,
email.Util.formataddr should learn to format unicode
strings, too. Likewise, parseaddr could grow a parameter
do_unicode, or a second function parseaddr_unicode could be
added. There is IMO no need for a new class.

In addition, this patch lacks documentation and test cases.

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Oops, test cases are there - only documentation is lacking.

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I think that adding options to the existing APIs simply makes the Unicode
support feel tacked on (as it would be). It is also error prone, where if
you are following best practice and using Unicode everywhere, you have
to remember to explicitly pass the 'do_unicode=True' parameter to this
one particular function.

I think the alternative approach would be to use a codec, similar to how
Unicode DNS domains are handled
('foo@example.com'.decode('emailaddress')).

I still prefer the OO approach though, as it allows the programmer to
treat email addresses as a standard Unicode string with a few extra
features, such as the __cmp__ method I've since added to
EmailAddress.py and the test suite:

>>> e = EmailAddress(u'renee@ol\u00e9.de', u'Rene\u00e9 Acut\u00e9')
>>> e == str(e)
True
>>> e == unicode(e)
True
>>> e == str(EmailAddress(e.upper()))
True
>>> e == unicode(EmailAddress(e.upper()))
True

I'm assigning this to myself so I don't lose it. I'll need to incorporate the intent of the tests and logic into email6. And yes I set 3.3 on purpose...email6 won't be in 3.2 and I don't want to spend the cycles figuring out whether this would work in email5 (the 3.2 version of email).

bpo-1690608 addresses part of this issue, and bpo-11783 will address the IDNA part.

From my point of view those two issues solve this problem from the perspective the email package infrastructure and *current* API. In the email6 API I do plan to have an address helper class that will make managing addresses more conveniently OO, but that is part of the whole email6 process and I don't feel a need any longer to keep this issue open. There's no good value for 'resolution' to express the resolution here (I've accepted the idea but not the code), so I used 'remind', since I will be coming back to the idea in a little while.