Check that domain of email addresses can be resolved

email_verifier.py

#!/usr/bin/python
"""
Takes a csv of email addresses and gives back a csv of the email addresses that have a resolvable domain.
"""

domains = list()
checked = []
checked_bad = []
    
import socket
import csv
file = open("good_emails.csv", "wb")
count = 0
with open("testfile.csv", "rb") as csvfile:
    spamwriter = csv.writer(file, delimiter=';',
                            quotechar='|', quoting=csv.QUOTE_NONE)
    spamreader = csv.reader(csvfile, delimiter=',', quotechar='|')
    for row in spamreader:
        for email in row:
            domain = email.split("@")[1].lower()
            try:
                count += 1
                if domain in checked:
                    spamwriter.writerow([email + ","])
                elif domain in checked_bad:
                    raise Exception
                else:
                    socket.gethostbyname(domain)
                    spamwriter.writerow([email + ","])
                    checked.append(domain)
                if count % 50 == 0:
                    spamwriter.flush()

                print "successful email is: " + repr(email) + "\n"
            except:
                checked_bad.append(domain)
                print "failed email is: " + repr(email) + "\n"