The messages above are very old and seem to be discussing Python 2. There is no `__unicode__` method any more, for example, though there is a `__str__` method which presumably does what `__unicode__` used to do. It is documented now at https://docs.python.org/3.10/library/email.header.html#email.header.Header.__str__ . You'll have to do some more digging to figure out whether the OP's complaint still applies.