How can I diagnose malfunctioning antispam blacklist server lookups?


-----Original Message-----

Date: Mon, 4 Jul 2005 21:22:56 -0300
To: "Claus Christensen"
Subject: RE: (Case 3768) AntiSpam Blacklists

Hi Claus,

I can browse to the blacklists just fine with Internet Explorer, which means that DNS is working fine, however it keeps saying that the blacklist failed during testing in POPcondmin and won't be used. How can I diagnose the  blacklists on my system and what does POPcon do to "test" them?





you are right - DNS lookups are used to check if a particular IP is listed in a blacklist. But the website for a particular list and the list itself are separate DNS entries, so successfully browsing to a lists site does not automatically indicate that the DNS lookup will work.

Before using a blacklist POPcon checks if the IP "" is listed - it should never be - and if it is that particular blacklist is not used. You can do the same check using the PING command in a CMD window:

This command will check if the IP is listed in bl.spamcop.net - the lookup should fail and not return an IP address:

C:\> ping

This command will check if the IP is listed - most (but unfortunately not all) blacklists will list this IP for testing purposes - the lookup should work and the IP "" is normally returned:

C:\> ping

If the first ping command does return an IP address something about your DNS setup is not correct - check routers, firewalls and use the IPCONFIG /ALL command to validate your network card setup.