Python - Fake Smtp and test email

January 1, 2021

Steps

End result. Save a test e-mail message to mail folder

b'From: From Person <from_email@test.com>
To: To Person <to_email@test.com>
Subject: Fake SMTP e-mail test

This is a fake e-mail message.'

Create fake-smtp.py and copy / paste following codes.

import argparse
import asyncore
import smtpd
from datetime import datetime
from pathlib import Path


def get_date_time_stamp():
    today = datetime.now()
    timestamp = str(today.timestamp()).split('.')[0]
    return f'{today:%m_%d_%Y}_{timestamp}' # 10_26_2021_1635302925

class FakeSMTPServer(smtpd.SMTPServer):
    def __init__(*args, **kwargs):
        smtpd.SMTPServer.__init__(*args, **kwargs)
        print ('Running fake smtp server')

    def process_message(*args, **kwargs):

        destination = Path.cwd() / f'mail/{get_date_time_stamp()}.eml'
        
        with open (destination, 'w') as file:
            file.writelines(str(args[4]).replace('\\n', '\n')) # email content only and replace \n to newline

if __name__ == '__main__':

    parser = argparse.ArgumentParser()
    parser.add_argument('-s', '--server', type=str, default='127.0.0.1', help='server to listen on. Default 127.0.0.1')
    parser.add_argument('-p', '--port', type=int, default=2525, help='port to listen on. Default 2525.')
    args = parser.parse_args()
    # python fake_smtp.py -s 127.0.0.1 -p 2525
    
    smtp_server = FakeSMTPServer((args.server, args.port), None)
    
    try:
        asyncore.loop()
    except KeyboardInterrupt:
        smtp_server.close()

Create test-email.py and copy / paste following codes

import smtplib

from_email = 'from_email@test.com'
to_emails = ['to_email@test.com']

message = '''From: From Person <from_email@test.com>
To: To Person <to_email@test.com>
Subject: SMTP e-mail test

This is a fake e-mail message.
'''

if __name__ == '__main__':
    try:
        mail = smtplib.SMTP('127.0.0.1', 2525) # Enter host and port from fake_server.py
        mail.sendmail(from_email, to_emails, message)         
        print ('Successfully sent email')
    
    except:
        print ('Error: unable to send email')

Run fake-smtp.py. Ctrl + F5 or Right click >> "Run Python File in Terminal" within VS Code or run it manually if specific host and IP are required.
```
$ python fake_smtp.py -s 123.456.678.9 -p 25
```
Open a new terminal and run fake-email.py. Host and port must match with fake-smtp.py
```
$ python fake_email.py 
```

Python - Fake Smtp and test email

Steps

Github