Python/smtpd

smtpd

smtpd – Sample SMTP Servers - Python Module of the Week - https://pymotw.com/2/smtpd/

Server:

# smtpd-server.py
import smtpd
import asyncore

class CustomSMTPServer(smtpd.SMTPServer):
    
    def process_message(self, peer, mailfrom, rcpttos, data):
        print 'Receiving message from:', peer
        print 'Message addressed from:', mailfrom
        print 'Message addressed to  :', rcpttos
        print 'Message length        :', len(data)
        return

server = CustomSMTPServer(('127.0.0.1', 1025), None)

asyncore.loop()

Client:

# smtpd-client.py
import smtplib
import email.utils
from email.mime.text import MIMEText

# Create the message
msg = MIMEText('This is the body of the message.')
msg['To'] = email.utils.formataddr(('Recipient', 'recipient@example.com'))
msg['From'] = email.utils.formataddr(('Author', 'author@example.com'))
msg['Subject'] = 'Simple test message'

server = smtplib.SMTP('127.0.0.1', 1025)
server.set_debuglevel(True) # show communication with the server
try:
    server.sendmail('author@example.com', ['recipient@example.com'], msg.as_string())
finally:
    server.quit()

This worked on Windows, and was a great way to trick Outlook into thinking there was a SMTP server for an inbound only account.