I ask this, in all innocence, because I really miss the old one.
Almost any subject you can think of has a dozen or more associated mailing lists.
For security issues, there's bugtraq (and the fifty other groups that Security Focus hosts), there's Full Disclosure (another place where I have Gadi kill filed), and there are excellent resources such as InfoSec News, the Dataloss mailing list, Firewall Wizards... I could go on, but I'll stop.
Nearly every reputable vendor has announcement lists that just tell you about their patches. This is also true for many of the open source operations (such as OpenBSD, Slackware, Drupal, and so on).
I read close to a hundred mailing lists, and monitor as many more. Still, there's at least three or four hundred more that I could be subscribed to, but there just isn't that much additional value, so I don't.
NANOG-L is unique. There isn't anything else devoted to issues for truly large networks, and the providers that manage the distance between them. When I see Cisco (or Juniper, or Extreme) announcements about a vulnerability, those are useful. Nonsense about Solaris 10 telnet vulnerabilities, or FedGov meetings, or requests for someone from Comcast to please call (and what is it with Comcast, anyway?). I am sure that I could get some of the interesting discussions that I see here, on other lists, but I doubt that they'd have the same population (that is, if the last spate of crazies hasn't driven them all off).
*DON'T* change the aup. It's fine the way it is. On the other hand, administratively prohibiting any post from certain repeat offenders without someone reviewing it might be nice.
Clearly I have not yet had enough coffee. -- Any commercial institution that is serious about protecting their customers from phishing will stop sending mail marked up with HTML.
