Validating Email Addresses by checking their domain.

gistfile1.py

#!/usr/bin/python

import sys
import socket
import os
import re

DEBUG_MODE=False
OUPUT_FILENAME="bad_domains.txt"

__query = 'nslookup -q=mx {0}'

FILENAME=sys.argv[1]

def isGarbage(line):
  if line.startswith("---") or line.endswith("rows)") or line.startswith("domain") or len(line)==0:
     return True
  else:
     return False

def canResolveDomain(domain):
  try:
     ipAddress=socket.gethostbyname(domain)
     return True
  except socket.gaierror:
     return False

def check_for_mx_record(domain):
    command = __query.format(domain)
    with os.popen(command) as response:
        result = response.readlines()
        for line in result:
            if line.find("mail exchanger")>-1:
               print domain,line
               return True
    return False


with open(FILENAME) as inputFile:
  with open(OUPUT_FILENAME,"w") as outputFile:
    domains=set(inputFile)
    for line in domains:
        line=line.strip()
        if isGarbage(line):
          continue
        domain=line
        hasMXHosts=check_for_mx_record(domain)
        print domain, hasMXHosts
        if not hasMXHosts:
            print >>outputFile,domain