Die Dokumentation ist eher unvollständig. Ich konnte die eingehende E-Mail nicht einrichten. Hier sind einige Details:

app.yaml:

handlers:

- url: /_ah/mail/owner@oladic\.appspotmail\.com
  script: handle_owner.py
  login: admin

- url: /_ah/mail/support@oladic\.appspotmail\.com
  script: handle_support.py
  login: admin

- url: /_ah/mail/.+
  script: handle_catchall.py
  login: admin

- url: .*
  script: main.py

inbound_services:
- mail

handle_catchall.py:

# To change this template, choose Tools | Templates
# and open the template in the editor.

import logging, email

from google.appengine.api import mail
from google.appengine.ext import webapp
from google.appengine.ext.webapp.util import run_wsgi_app
from google.appengine.ext.webapp.mail_handlers import InboundMailHandler

class LogSenderHandler(InboundMailHandler):
    def receive(self, mail_message):
        logging.info("================================")
        logging.info("Received a message from: " + mail_message.sender)
        plaintext_bodies = message.bodies('text/plain')
        html_bodies = message.bodies('text/html')

        for content_type, body in html_bodies:
            decoded_html = body.decode()
            logging.info("content_type: " + content_type)
            logging.info("decoded_html: " + decoded_html)

        attachments = []
        if message.attachments:
            if isinstance(message.attachments[0], basestring):
                attachments = [message.attachments]
            else:
                attachments = message.attachments

        logging.info("number of attachments: " + str(len(attachments)))

        for filename, content in attachments:
            logging.info("plaintext_bodies: " + plaintext_bodies)
            logging.info("filename: " + filename)
            content

        logging.info("--------------------------------")



def main():
    application = webapp.WSGIApplication([LogSenderHandler.mapping()], debug=True)
    wsgiref.handlers.CGIHandler().run(application)


if __name__ == '__main__':
    main()