pyramid mailer incorrectly encodes from-header if international characters exist

[ztane]

Python 3.10, if relevant,

>>> m = pyramid_mailer.message.Message(sender='ÄÖ <foo@bar>', recipients=['baz@quux'], body='foo')
>>> print(m.to_message().as_string())
Content-Type: text/plain; charset="us-ascii"
MIME-Version: 1.0
Content-Transfer-Encoding: quoted-printable
From: =?utf-8?b?w4TDliA8Zm9vQGJhcj4=?=
To: baz@quux
Content-Disposition: inline

foo

The header is incorrectly quoted, the quoting must not affect the actual header. For example Amazon SES is unable to handle this. Not sure if anything else would either. I guess the fix would be to use the email.message.EmailMessage from Python 3.6+.