login_tests.py

# Assumes user/pass of admin/aaa, md5 hashed in the server password file

def logincram(user='admin', password='47bce5c74f589f4867dbd57e9ca9f808', port=2025):
    s = smtplib.SMTP(host='localhost', port=port)
    s.ehlo()
    s.esmtp_features["auth"] = 'CRAM-MD5'
    s.debuglevel = 5
    s.login(user, password)
    
def loginplain(user='admin', password='aaa', port=2025):
    s = smtplib.SMTP(host='localhost', port=port)
    s.ehlo()
    s.esmtp_features["auth"] = 'LOGIN'
    s.debuglevel = 5
    s.login(user, password)    

simple_smtp.py

import os, md5

from twisted.mail import mail, relaymanager, imap4
from twisted.cred import checkers, credentials
from twisted.python import log
from twisted.application import internet
from twisted.application import service
from twisted.internet import defer


SMTP_PORT = 2025
QUEUE_PATH = './users_home/insertionQueue'

if not os.path.exists(QUEUE_PATH):
    os.makedirs(QUEUE_PATH)

def _hash(name, clearpsw, hashedpsw):
    return md5.md5(clearpsw).hexdigest()

class MyFilePasswordDB(checkers.FilePasswordDB):
    def __init__(self, filename, delim=':', usernameField=0, passwordField=1,
                 caseSensitive=True, hash=None, cache=False):
        checkers.FilePasswordDB.__init__(self, filename, delim, usernameField, passwordField,
                 caseSensitive, hash, cache)
        
        self.credentialInterfaces = (
            credentials.IUsernamePassword,
            credentials.IUsernameHashedPassword
        )        

    def requestAvatarId(self, c):
        try:
            u, p = self.getUser(c.username)
        except KeyError:
            return defer.fail(error.UnauthorizedLogin())
        else:

            up = credentials.IUsernamePassword(c, None)
            
            if self.hash and credentials.IUsernameHashedPassword(c, None) is None:
                if up is not None:
                    h = self.hash(up.username, up.password, p)
                    if h == p:
                        return defer.succeed(u)

                return defer.fail(error.UnauthorizedLogin())
            else:
                return defer.maybeDeferred(c.checkPassword, p
                    ).addCallback(self._cbPasswordMatch, u)


smtpusers = MyFilePasswordDB('smtppasswords.txt', caseSensitive=True, hash=_hash, cache=True)

mailservice = mail.MailService()
mailservice.setQueue(relaymanager.Queue(QUEUE_PATH))
mailservice.smtpPortal.registerChecker(smtpusers)
smtpserver = mailservice.getESMTPFactory()
# Add PLAIN auth challenger
smtpserver.challengers['PLAIN'] = imap4.PLAINCredentials
application = service.Application("Console SMTP Server")
internet.TCPServer(SMTP_PORT, smtpserver).setServiceParent(application)