forward emails to an real smtp server

smtp_forwarder.py

import smtpd
import asyncore
import smtplib
from email.message import EmailMessage
from email.parser import Parser, BytesParser
from email.policy import default
from base64 import b64decode


# Configuration for the real SMTP server
REAL_SMTP_SERVER = 'REAL_SMTP_SERVER'
REAL_SMTP_PORT = 587
REAL_SMTP_USERNAME = 'REAL_SMTP_USERNAME'
REAL_SMTP_PASSWORD = 'REAL_SMTP_PASSWORD'

# Local server configuration
LOCAL_SMTP_PORT = 25  # Port for the local SMTP server


class SMTPProxyServer(smtpd.SMTPServer):
    def process_message(self, peer, mailfrom, rcpttos, data, **kwargs):
        print(f"Received email from: {mailfrom}")
        print(f"Recipients: {rcpttos}")

        # Ensure data is parsed from bytes to an email message
        email_message = BytesParser(policy=default).parsebytes(data)

        # Forward the email to the real SMTP server
        try:
            with smtplib.SMTP(REAL_SMTP_SERVER, REAL_SMTP_PORT) as smtp:
                smtp.starttls()
                smtp.login(REAL_SMTP_USERNAME, REAL_SMTP_PASSWORD)

                # Send the email
                smtp.send_message(email_message, from_addr=mailfrom, to_addrs=rcpttos)

            print("Email forwarded successfully.")
        except Exception as e:
            print(f"Failed to forward email: {e}")

# Set up the proxy server
def run_server():
    server = SMTPProxyServer(('0.0.0.0', LOCAL_SMTP_PORT), None)
    print(f"SMTP Proxy Server listening on port {LOCAL_SMTP_PORT}")
    asyncore.loop()

if __name__ == "__main__":
    run_server()