def _get_envelope(self, email_number):
logging.info("loading email {}".format(email_number))
response, email_data = self.mail.uid("fetch", email_number, "(RFC822.HEADER)")
message = email.message_from_bytes(email_data[0][1])
envelope = Envelope()
envelope.number = email_number
envelope.time = message["Date"]
envelope.sender = self._decode(message["From"])
envelope.subject = self._decode(message["Subject"])
logging.info("loaded {}".format(envelope))
return envelope
