mail-addons/mailgun/models/mail_thread.py

import requests

from odoo import models, api


import logging
_logger = logging.getLogger(__name__)


class MailThread(models.AbstractModel):
    _inherit = 'mail.thread'

    @api.model
    def mailgun_fetch_message(self, message_url):
        api_key = self.env['ir.config_parameter'].sudo().get_param('mailgun.apikey')
        res = requests.get(message_url, headers={'Accept': 'message/rfc2822'}, auth=('api', api_key), verify=False)
        self.message_process(False, res.json().get('body-mime'))