Script to check that a list of email address have valid domains (i.e. they have an MX record)

emailchecker.py

# pip install pydns
import DNS, smtplib
import csv, re

in_filename = 'input.csv'
skip_to = None


# DNS.DiscoverNameServers()
DNS.defaults['server'].append('208.67.222.222')
DNS.defaults['server'].append('208.67.222.220')
DNS.defaults['timeout'] = 5

cached_lookups = {}
# import pdb; pdb.set_trace()
def has_mx(hostname):
    if hostname in cached_lookups.keys():
        return cached_lookups[hostname]
    result = False
    i = 0
    while i < 3:
        i = i+1
        DNS.defaults['timeout'] = i+2
        try:
            mx_hosts = DNS.mxlookup(hostname)
            result = (len(mx_hosts) > 0)
        except DNS.Base.ServerError as e:
            if e[1] == 3 or e[1] == 2:
                result = False
            else:
                raise
        except DNS.Base.TimeoutError:
            # print "(timeout on %s)" % hostname
            continue
        break
    # except DNS.Base.TimeoutError:
    #     result = True
    cached_lookups[hostname] = result
    return result

input = file(in_filename,'rU')
c = csv.reader(input)
if skip_to:
    for row in c:
        if row[0] == skip_to:
            break
for row in c:
    email = row[0]
    # print email
    m = re.match(r"^.+?@(.+\..+)$", email)
    if not m:
        # print "invalid: %s" % email
        print "%s,INVALID" % email
    else:
        domain = m.group(1)
        # print "%s - %s: %s" % (email,domain,has_mx(domain))
        try:
            print "%s,%s" % (email, has_mx(domain))
        except DNS.Base.TimeoutError:
            print "%s,TIMEOUT" % email
            continue

https://github.com/syrusakbary/validate_email looks good as well