Hello, kind of new here.

I just wanted to note that the issue that lead to Tchap's security attack still exists in the non-deprecated message_from_string function:

email.message_from_string('From: a@malicious.org@important.com', policy=email.policy.default)['from'].addresses

(Address(display_name='', username='a', domain='malicious.org'),)

So, deprecating parseaddr is not enough for security purpose, unless there is another ticket for the new email API.