Forum Moderators: phranque
These are generally a mix of security professionals, administrators etc. and although they are mailing lists rather than newsletters, the traffic normally isn't very high and you should be able to choose to take a digest version instead of recieving every single message.
Generally the atmosphere on there is similar to here with people willing to help out others etc, the major difference is that because each post is moderated you get a much better signal:noise ratio with very little off-topic material.
On top of that you have the various "digest" newsletters which attempt to put a common face to a large number annoucements - things like Securiteam and/or ISS X-Force Alert - these are too tabloid-y for my taste but they do cover a very wide variety of alerts rather than just a specific sub-set.
A quick google for any of those names should turn up the official sites with details of how to sign up.
Hope that helps.
- Tony