DNS Blacklist

One of my clients had their emailserver's IP blocked by several blacklist servers around the internet. Apparently, that IP has been sending spam and was detected by these blacklisters. The bungling administrator setup the server as the company's gateway AND mail server. That's me btw.

Thanks to www.dnsstuff.com I was able to determine which servers blacklisted my client.

Sites like this along with www.network-tools.com are invaluable to sysads who are troubleshooting problems like the above.