Use current version of python.
Python 3 compatibility.

Python 3 makes under-the-hood changes to the email library,
specifically implementing a "policy" system to enforce adherence to
the RFC standards for email.  One thing it doesn't like is headers
with multiple lines.  Since all I care about is trucation, just keep
everything on one line and cut it off beyond, say, 130 characters.
If the header is short, do nothing.