SMTP through Exchange using Integrated Windows Authentication (NTLM) using Python

Question

I want to use the credentials of the logged-in Windows user to authenticate an SMTP connection to an Exchange server using NTLM.

I\'m aware of the python-ntlm module

Answer 1

Python 2.7.x will fail on sending the NTLM Type 3 message due to the blank cmd specified:

code, response = smtp.docmd("", ntlm_message)

This ends up sending the correct response back to the server, however it pre-pends a space due to the nature of docmd() calling putcmd().

smtplib.py:

def putcmd(self, cmd, args=""):
    """Send a command to the server."""
    if args == "":
        str = '%s%s' % (cmd, CRLF)
    else:
        str = '%s %s%s' % (cmd, args, CRLF)
    self.send(str)

# ...

def docmd(self, cmd, args=""):
    """Send a command, and return its response code."""
    self.putcmd(cmd, args)
    return self.getreply()

which as a result takes the path of the else condition, thereby sending str(' ' + ntlm_message + CRLF) which results in (501, 'Syntax error in parameters or arguments').

As such the fix is simply to send the NTLM message as the cmd.

code, response = smtp.docmd(ntlm_message)

A fix to the above answer was submitted, though who knows when it will be reviewed/accepted.