Quoting Barry's message from issue 10839: On Jun 13, 2016, at 06:38 AM, Berker Peksag wrote: >I don't know if it's a good idea or API but can we add a 'policy' keyword >argument to email.mime.base.MIMEBase? Right now, this is the only way to >change the default policy without using high level functions like >email.message_from_string(): > > m = MIMEMultipart() > m.policy = email.policy.default I think we just need to plumb a `policy` argument through to the ultimate base class, email.message.Message