Spamhaus periodically places some IP addresses back on their "PBL" which leads certain mail exchanges to treat mail originating from the IP address as suspicious. If you run a mail server that ends up on this PBL you'll probably just notice that certain mail stops making it all the way to recipients. This python script checks the block status fo…

spamhaus-check.py

#!/usr/bin/python

import os
import sys
import urllib

# Change this to match your mail server's REVERSE static IP address
staticIPAddress = "1.0.0.127"

# Change this to an email address you don't mind sending to and from for the notice alert delivery
toFromMailAddress = "somebody@example.com"

### Spamhaus blocks IP addresses using DNSBL that is all distributed via standard DNS records.
### e.g. if you lookup a reverse-ip prepended blacklist URL:
###
### > dig -t a 1.0.0.127.zen.spamhaus.org
###
### You'll only get a found record if the IP address (127.0.0.1) IS in one of Spamhaus's blacklists.
### 
### I'm using "dig" on my system to script this, but you might consider using a DNS library for python or another method.

# Lookup the pertinent DNS query to determine if the specified IP address is listed. Technically 
# we should be looking up the A record first, but in my tests the TXT record will contain the URL
# for the pertinent blacklist information only when the IP address is in fact listed on some 
# blacklists.

dnsHostname = staticIPAddress + ".zen.spamhaus.org"
p = os.popen("dig +short -t TXT " + dnsHostname)
lookupResult= p.read()

# If the IP address is not listed in any Spamhaus lists, the string is empty!
notListed = (len(lookupResult) == 0)

if (notListed is False):
        msg = """To: %s
From: %s
Subject: Spamhaus spam list addition alert

The IP address %s has unfortunately been added to one of the lists maintained by the Spamhaus project.

For more information, visit the pertinent Spamhaus info URL: %s""" % (toFromMailAddress, toFromMailAddress, staticIPAddress, lookupResult)
        SENDMAIL = "/usr/sbin/sendmail" # sendmail location
        p = os.popen("%s -t -i" % SENDMAIL, "w")
        p.write(msg);
        p.close()

        print msg