New Python 3 email API

In the latest releases of Python the email package was redesigned. It is now more user-friendly, making the complicated topic of emails encodings easier to approach.

For instance the old API required internationalized headers to be decoded manually:

>>> import email
>>> data = b'Subject: Asperges pour le =?utf-8?q?d=C3=A9jeuner?=\n\n'
>>> m = email.message_from_bytes(data)
>>> m['Subject']
'Asperges pour le =?utf-8?q?d=C3=A9jeuner?='

The new API takes care of this automatically:

>>> import email
>>> from email import policy
>>> data = b'Subject: Asperges pour le =?utf-8?q?d=C3=A9jeuner?=\n\n'
>>> # For backward compatibility reasons, the policy needs
>>> # to be passed explicitly to use the new API
>>> m = email.message_from_bytes(data, policy=policy.default)
>>> m['Subject']
'Asperges pour le déjeuner'