'Send a message from a user, to a user.
:param sender:
The :class:`User` which sends the message.
:param um_to_user_list:
A list which elements are :class:`User` to whom the message is for.
:param message:
String containing the message.'

def send_message(self, sender, um_to_user_list, body):

    msg = self.model(sender=sender, body=body)
    msg.save()
    msg.save_recipients(um_to_user_list)
    msg.update_contacts(um_to_user_list)
    signals.email_sent.send(sender=None, msg=msg)
    return msg
