My boss had an email he sent rejected yesterday because of a dnsbl. Here's what's really strange about this. 1. His ISP is Comcast. 2. The netblock his actual IP address is located in begins 74.93. It's a static IP and been in use for several years. 3. His reported computer's host name is xxxxxx.comcast.net 4. A dns lookup on his computer's host name returns an IP address starting with 204. That's using 6 different name servers belonging to as many different domains. 5. A whois on the 204. IP address returns the network owner as AT&T WorldNet, not Comcast. Has anyone ever seen anything even remotely resembling this? I'm really stumped as to what is going on here. I've never seen anything like it. It looks like it might possibly be cache poisoning of name servers, but that would mean some major ISP's and some very well known dns servers have big problems with respect to dns. I have pointed my internal dns servers to several different name servers to use as forwarders for resolving url's outside my internal network, and all them return the same thing. The dns servers our business servers utilize, Comcast's, return the same thing mine do.