code: def send(sender_instance):
      
      m = Mailin(
          "https://api.sendinblue.com/v2.0",
          sender_instance._kwargs.get("api_key")
      )
      data = {
          "to": email_list_to_email_dict(sender_instance._recipient_list),
          "cc": email_list_to_email_dict(sender_instance._cc),
          "bcc": email_list_to_email_dict(sender_instance._bcc),
          "from": email_address_to_list(sender_instance._from_email),
          "subject": sender_instance._subject,
      }
      if sender_instance._template.is_html:
          data.update({
              "html": sender_instance._message,
              "headers": {"Content-Type": "text/html; charset=utf-8"}
          })
      else:
          data.update({"text": sender_instance._message})
      if "attachments" in sender_instance._kwargs:
          data["attachment"] = {}
          for attachment in sender_instance._kwargs["attachments"]:
              data["attachment"][attachment[0]] = base64.b64encode(attachment[1])
      result = m.send_email(data)
      if result["code"] != "success":
          raise SendInBlueError(result["message"])
docs: Send a transactional email using SendInBlue API.
  
      Site: https://www.sendinblue.com
      API: https://apidocs.sendinblue.com/