How to send an email from a GCP Cloud Function

Question

I am trying to send an email from a GCP Cloud Function using an AWS Simple Email Service. My code works locally using a dummy request class. Once I deploy the Cloud Function I get a strange error : Function cannot be initialized. Error: function terminated. and I get another error Can't connect to (<my_host>, 8080) even though I specified the environment variable SMTP_PORT = <my_port>. Here is my code :

# ----------------------------------------------------------------------------------------------------
# main.py file for a Cloud function sends alert email to users.
# Example run:
# > export USERNAME=username
# > export PASSWORD=*****
# > python main.py
# > export SENDER=<email_sender>
# > export SMTP_PORT=<my_port>
# > export HOST=<my_host>
# ----------------------------------------------------------------------------------------------------

import logging
import os
import smtplib
from datetime import datetime

from dummy_request import DummyRequest


def main(request):
    """
    Obtains username and password from the environment and gets an API token from that.
    Triggered by a HTTP call. loud Scheduller was used in production.
    """

    username = os.environ.get(
        'USERNAME', 'Specified environment variable is not set.')
    password = os.environ.get(
        'PASSWORD', 'Name of the pipeline to trigger.')
    sender = os.environ.get(
        'SENDER', 'Email that will send pipeline alert.')
    host = os.environ.get(
        'HOST', 'SMTP host.')
    smtp_port = int(os.environ.get(
        'SMTP_PORT', 'SMTP port.'))

    # Setup logger
    logging.basicConfig(level=logging.DEBUG)

    logging.info(f'Parsing the input request.')

    request_json = request.get_json()
    logging.debug(f'Payload {request_json}')

    content_type = request.headers['Content-Type']
    logging.debug(f'Header Content tpye {request_json}')

    if content_type == 'application/json':

        receiver = request_json["receiver"]

        logging.info(f'Sending email to : {receiver} from {sender}.')

        # Create smtp client obejct
        s = smtplib.SMTP(host=host, port=smtp_port)

        logging.info(f'Connecting to the smtp host.')
        s.connect(host=host, port=smtp_port)

        logging.info(f'Setting up TLS.')
        s.starttls()

        logging.info(f'Logging in to server.')
        s.login(username, password)

        # Setup message
        message = f'Attention ! '

        send_message = f'From: {sender}\nTo: {receiver}\nSubject: Testing\n\n{message}'

        s.sendmail(sender, receiver, send_message)

        response = f'Email sent to {receiver}'

    else:
        logging.error(
            'Payload is not JSON, please include header : {"content-type": "application/json"}')
        response = 'Email not sent.'

    return response


if __name__ == '__main__':
    # Setup dummy request
    request = DummyRequest()

    print(main(request))

It seems that the code is trying to connect to <my_host>:8080 when it should be connecting to <my_host>:<my_port>, I really cannot understand why. The Python version I use locally and in the Cloud Function are the same (both equal to Python 3.7).