How to Send an Email with smtplib and a Mock Server in Python

import smtplib
from email.message import EmailMessage
import aiosmtpd.controller as controller
import threading


def handle_message(server, session, envelope):
    print(f"Mock server received message:")
    print(f"From: {envelope.mail_from}")
    print(f"To: {envelope.rcpt_tos}")
    print(f"Subject: {envelope.content.decode()}")
    return '250 OK'


def main():
    # Start mock SMTP server on port 1025
    mock_server = controller.Controller(handler=handle_message, hostname='127.0.0.1', port=1025)
    mock_server.start()
    print("Mock SMTP server started on 127.0.0.1:1025")

    # Create email message
    msg = EmailMessage()
    msg.set_content("Hello, this is a test email sent with smtplib!")
    msg['Subject'] = "Test Email"
    msg['From'] = "sender@example.com"
    msg['To'] = "recipient@example.com"

    # Send email via mock server
    with smtplib.SMTP('127.0.0.1', 1025) as client:
        client.send_message(msg)

    print("Email sent successfully via mock server")
    mock_server.stop()


if __name__ == "__main__":
    main()