Python aiosmtpd gives SMTP AUTH extension not supported by server

Question

I am trying to setup a SMTP server on my PC which should require authentication(just like gmail does). Attempting send email from client gives - "SMTP AUTH extension not supported by server". I took help from python aiosmtpd server with basic authentication and https://github.com/aio-libs/aiosmtpd/blob/master/examples/authenticated_relayer/server.py .

Server Code -

import os
import ssl
import subprocess
from aiosmtpd.smtp import SMTP
from aiosmtpd.controller import Controller
from aiosmtpd.handlers import Debugging
from aiosmtpd.smtp import AuthResult, LoginPassword


def auth_myauthenticator(server, session, envelope, mechanism, auth_data):
    print("call-----------")
    assert isinstance(auth_data, LoginPassword)
    username = auth_data.login
    password = auth_data.password    
    
    return AuthResult(success=True)


context = ssl.create_default_context(ssl.Purpose.CLIENT_AUTH)
context.load_cert_chain('cert.pem', 'key.pem')

class CustomController():

    def handle_data(self, server, session, envelope, data):
        print("Handle data-----------------------------------------")
        
        
controller = Controller(CustomController(),hostname='127.0.0.1', port=809, ssl_context=context,
        authenticator=auth_myauthenticator , auth_required= True)
controller.start()

input('Running. Press enter to stop.\n')
controller.stop()

Client Code -

import smtplib

sender = "xxx@gmail.com"
reciever = 'yyyy@gmail.com'

try:
   smtpObj = smtplib.SMTP_SSL('127.0.0.1',809)  
   smtpObj.login(sender,password)
   smtpObj.sendmail(sender, reciever, "Hii")
   print("Successfully sent email")
except Exception as e:
   print("Error: unable to send email", e)

Using this smtplib.SMTP_SSL('smtp.gmail.com',465) in the client code I was able to send email via gmail.

Also tried commenting just to debug

smtpObj.login(sender,password)

Error: unable to send email (530, b'5.7.0 Authentication required', 'xxxxx@gmail.com')

score 0 · Answer 1 · answered Feb 27 '23 at 15:44

ssl_context is an argument that Controller passes to the underlying asyncio server. I encountered a similar issue using this argument and instead opted to use the tls_context argument that gets passed to the underlying SMTP object. Making this change, I encountered an error ssl.SSLError: [SSL: WRONG_VERSION_NUMBER]. Easiest way to fix this was to instead of using SMTP_SSL use SMTP and then activate TLS through starttls().

So my suggestion is to change

controller = Controller(... , ssl_context=context, ...)

into

controller = Controller(... , tls_context=context, ...)

and also change

smtpObj = smtplib.SMTP_SSL('127.0.0.1',809)

into

smtpObj = smtplib.SMTP('127.0.0.1',809)
smtpObj.starttls()

and see if that helps.

Python aiosmtpd gives SMTP AUTH extension not supported by server

1 Answers1