Return a new ``Message`` instance. The arguments are 
        passed to the ``marrow.mailer.Message`` constructor.

def new(self, **kwargs):
        '''Return a new ``Message`` instance. The arguments are 
        passed to the ``marrow.mailer.Message`` constructor.'''
        app = self.app or current_app
        mailer = app.extensions['marrowmailer']
        msg = mailer.new(**kwargs)
        msg.__class__ = Message
        return msg