使用Gmail API和Python回复电子邮件

Question

我正在尝试使用Gmail API发送电子邮件回复。我写了以下代码，它不回复电子邮件，而是作为新邮件发送。

def create_message_with_attachment(
    sender, to,cc, subject, message_text, file):
  """Create a message for an email.

  Args:
    sender: Email address of the sender.
    to: Email address of the receiver.
    subject: The subject of the email message.
    message_text: The text of the email message.
    file: The path to the file to be attached.

  Returns:
    An object containing a base64url encoded email object.
  """
  message = MIMEMultipart()
  message['to'] = to
  message['from'] = sender
  message['subject'] = subject
  message['cc'] = cc

  msg = MIMEText(message_text)
  message.attach(msg)

  content_type, encoding = mimetypes.guess_type(file)

  if content_type is None or encoding is not None:
    content_type = 'application/octet-stream'
  main_type, sub_type = content_type.split('/', 1)
  if main_type == 'text':
    fp = open(file, 'rb')
    msg = MIMEText(fp.read(), _subtype=sub_type)
    fp.close()
  elif main_type == 'image':
    fp = open(file, 'rb')
    msg = MIMEImage(fp.read(), _subtype=sub_type)
    fp.close()
  elif main_type == 'audio':
    fp = open(file, 'rb')
    msg = MIMEAudio(fp.read(), _subtype=sub_type)
    fp.close()
  else:
    fp = open(file, 'rb')
    msg = MIMEBase(main_type, sub_type)
    msg.set_payload(fp.read())
    fp.close()
  filename = os.path.basename(file)
  msg.add_header('Content-Disposition', 'attachment', filename=filename)
  message.attach(msg)
  encoders.encode_base64(msg)
  encoded_message = urlsafe_b64encode(message.as_bytes())
  raw_msg= {'raw': encoded_message.decode()}
  raw_msg['threadId']= '16a7c412848d632d'
  return raw_msg

已发送的电子邮件显示在我的邮箱中的线程下方，但对于收件人，它以新邮件的形式发送，而不是他之前发送的邮件的下方。