On Fri, 2005-04-01 at 21:04 -0600, Mark A. Lewis wrote: > > Riight. Ever done a reverse lookup on a RR IP? Rogers? SBC? All of > them > will have valid reverse entries. See below. http://searchcio.techtarget.com/sDefinition/0,,sid19_gci917504,00.html "Reverse DNS (rDNS) is a method of resolving an IP address into a domain name, just as the domain name system (DNS) resolves domain names into associated IP addresses. One of the applications of reverse DNS is as a spam filter. Here's how it works: Typically, a spammer uses an invalid IP address, one that doesn't match the domain name. A reverse DNS lookup program inputs IP addresses of incoming messages to a DNS database. If no valid name is found to match the IP address, the server blocks that message."