Information on checking to see if an IP address is on any blocklists.

http://dnsbllookup.com

http://www.v-nessa.net/2010/07/16/simple-php-script-for-rbl-checking

http://codepad.org/R8M3dotF

https://www.projecthoneypot.org/

http://forums.cpanel.net/f185/google-blacklist-check-script-357921.html

http://www.google.com/safebrowsing/diagnostic?site=sonoracomm.com

https://www.google.com/webmasters/tools/home?hl=en

https://github.com/juliensobrier/google-safe-browsing-lookup-python

http://fixitscripts.com/problems/blacklist-check

http://snipplr.com/view/64564/

http://www.blmonitor.net/?p=17

http://www.freeblacklistmonitor.com/

• Up to 10 hosts free
• $9.95 per month for unlimited

http://www.ipchecks.net/

https://www.rblmon.com/

http://mxtoolbox.com/services_servermonitoring2.aspx

The Nagios monitoring platform has plugins available to check for blacklisting.

http://exchange.nagios.org/directory/Plugins/Email-and-Groupware#/

http://www.nagios.com/solutions/email-monitoring

http://exchange.nagios.org/directory/Plugins/Email-and-Groupware/check_rbl/details

http://exchange.nagios.org/directory/Plugins/Security/check_dnsbl/details