However, maybe that 5.1 message.py thing doesn't like header.Header instances.  Also extending msg128846, this one is related to the str() issue - added an extended email_message.2.patch.

  Traceback (most recent call last):
    File "/Users/steffen/usr/bin/s-postman.py", line 953, in save_ticket
      mb.add(ticket.message())
    File "/Users/steffen/usr/opt/py3k/lib/python3.2/mailbox.py", line 595, in add
      self._toc[self._next_key] = self._append_message(message)
    File "/Users/steffen/usr/opt/py3k/lib/python3.2/mailbox.py", line 733, in _append_message
      offsets = self._install_message(message)
    File "/Users/steffen/usr/opt/py3k/lib/python3.2/mailbox.py", line 805, in _install_message
      self._dump_message(message, self._file, self._mangle_from_)
    File "/Users/steffen/usr/opt/py3k/lib/python3.2/mailbox.py", line 215, in _dump_message
      gen.flatten(message)
    File "/Users/steffen/usr/opt/py3k/lib/python3.2/email/generator.py", line 88, in flatten
      self._write(msg)
    File "/Users/steffen/usr/opt/py3k/lib/python3.2/email/generator.py", line 134, in _write
      self._dispatch(msg)
    File "/Users/steffen/usr/opt/py3k/lib/python3.2/email/generator.py", line 151, in _dispatch
      main = msg.get_content_maintype()
    File "/Users/steffen/usr/opt/py3k/lib/python3.2/email/message.py", line 530, in get_content_maintype
      ctype = self.get_content_type()
    File "/Users/steffen/usr/opt/py3k/lib/python3.2/email/message.py", line 518, in get_content_type
      ctype = _splitparam(value)[0].lower()
    File "/Users/steffen/usr/opt/py3k/lib/python3.2/email/message.py", line 53, in _splitparam
      a, sep, b = param.partition(';')
  Exception: AttributeError: 'Header' object has no attribute 'partition'

P.S.: i'm hard to take, and 'programming is an iterative task'...