Ah, yes that workaround works. Thanks!

So what's the exact status of this policy? It's called the default policy, but it's not used by default?

If I download the latest version of python, will this be parsed correctly without explicitly setting the policy?

i.e. Is this still something that should be changed in the code?

(Yes, I already use message_from_bytes in my real application. I just used message_from_string in the MWE, because I could only attach one file in this web page, so I embedded the email body as a string in the script.)