[ekpyrotic]

I don't know much when it comes to ips, i.e., I can't tell whether that is a shared ip, or otherwise.

Nonetheless, a quick search reveals this individual (http://www.scamwarners.com/forum/viewtopic.php?f=34&p=32...) used/had that ip 3 months ago. (S)he appears to be a security specialist, which goes with the impression I got from the email.

[blasdel]

You're right, you don't know much about IP addresses. The entire 10.x.x.x block was reserved long ago for use on private networks, it's not routed anywhere on the internet. This RFC from 1996 describing best practices for their use is still accurate: http://tools.ietf.org/html/rfc1918

All of those addresses in the header posted are hosts within one of Google's networks. The same address is likely in use on other such networks.