python3 use google-app-engine receive email, how to configure to specific app, not default app

Question

I am able to receive eamil at the default service of google-app-engine, the address is [email protected], but I need to send to a specific service, not the default service, how can I do that, below is my code, thanks in advance.

app.yaml

runtime: python39 
app_engine_apis: true 
service: target-service
inbound_services: 
- mail 
- mail_bounce

handle code:main.py

from flask import Flask, request
from google.appengine.api import wrap_wsgi_app
from google.appengine.api import mail
app = Flask(__name__)
app.wsgi_app = wrap_wsgi_app(app.wsgi_app, use_deferred=True)
@app.route('/_ah/mail/<path>', methods=['POST'])
def receive_mail(path):
    mail_message = mail.InboundEmailMessage(request.get_data())
    print("called")
    return 'Success'

Answer 1

Just tested this in Python2.7 but I believe it should work in Python3 (the principle should be the same when it comes to the mail part but might require a few tweaks for the other places)

1. I have a default service with an app.yaml file and another service called second-service with second-service.yaml.

2. Added the following to both app.yaml & second-service.yaml files

    inbound_services:
        - mail

3. Added this to second-service.yaml Note that my python file here is called second.py. It handles traffic routed to second-service

- url: /_ah/mail/.+
  script: second.app

4. Added this to app.yaml Note that my python file here is called ``main.py```.

- url: /_ah/mail/.+
  script: main.app

5. Added the following to both main.py and second.py

@app.route('/_ah/mail/<path>', methods=['POST'])
def receive_mail(path):
    mail_message = mail.InboundEmailMessage(request.get_data())
    logging.info(mail_message.subject)
    return 'Success'

6. For testing, I sent emails to the addresses below and they were only received by their respective services.

Note: I used -dot- and not . for the multi-service bit.

a) support@second-service-dot-<project_id>.appspotmail.com

b) support@<project_id>.appspotmail.com

Final bit: I only have service: second-service within second-service.yaml