Thanks for the prompt feedback. In Python 3.2, the closest equivalent for the illustrated issue I could find is: >>> from email.message import Message >>> from email.generator import Generator >>> from sys import stdout >>> m = Message() >>> m["Field"] = "x" * 100 >>> g0 = Generator(stdout, maxheaderlen=0) >>> gn = Generator(stdout, maxheaderlen=None) >>> g0.flatten(m) Field: xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx >>> gn.flatten(m) Field: xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx It may be the case that a documentation change is all that is needed. I'm not sure that this change would break compatibility since `max_line_length=None` for the policy is not the default value. Please advise further if I should just update the documentation and modify the test to guard for future changes.