Thanks for asking, because I didn't realize the list was still in business.

http://www.extropy.org/emaillists.htm

The longest running transhumanist email list in the world. Now entering its second decade, the Extropy-Chat (formerly "Extropians") Email List is open to ExI members and non-members alike. It is a general-purpose discussion forum.

I actually think they're entering their 3rd decade now. I was on it early to mid nineties.

They seem to have gone moderated - see ""EXTROPY-CHAT" LIST AGREEMENT:" on the right side of the page.

They had an elaborate user customized filtering mechanism. Usenet had regexp controlled field specific filtering. I think they built on that and went as far as transitive ranking - you could have a weighted filter of what selected people filtered.

To the extent that all the griping over signal to noise is about a desire to control what you see, and not control what others see and say, there are decades old solutions to discussion filtering. The fancy shmancy Web has been a marked deevolution of capabilities in this regard. It's pitiful. No web discussion forum I know of has filtering capabilities even in the ball park of Usenet, which was available in the 80s. Pitiful.