def METHOD_NAME(self):
    """Very simple envelope with a To, From, Subject, body and attachment.
    """
    headers = {
        'From': 'foo@example.com',
        'To': 'bar@example.com',
        'Subject': 'Test email',
    }
    e = envelope.Envelope(account=test_account,
                          headers={k: [v] for k, v in headers.items()},
                          bodytext='Test')
    with tempfile.NamedTemporaryFile(mode='wt', delete=False) as f:
        f.write('blah')
    self.addCleanup(os.unlink, f.name)
    e.attach(f.name)
    self._test_mail(e)