The benefits, if any, of supporting IPv6 now really depend on what kind of use your organization makes of the Internet. Despite all of the huffing and puffing, it will be a very long time before there are interesting bits of the net not visible over IPv4 for common applications like http and smtp. No matter how much NAT sucks in theory, for most non-technical users it's invisible and they have no reason to care. At this point, I'd say the mail selling point is that there are an increasing number of home users and particularly mobile users with native connections only in v6. If you're running services of interest to those users, you'll get better visibility about who they are over v6. Failing that, from a business point of view it's mostly handwaving and I wouldn't spend a lot of time trying to persuade them that there are practical advantages of adding v6 to an existing working v4 network. R's, John