Hmm, I'm not entirely sure. I can find old usenet comments - like my nethack YAFAP - from 2005 to 2008, but as far I can tell they were all made with Google Groups. I do vaguely recall using a newsreader, maybe trying to set up Thunderbird? It certainly would have been in character, "real men use newsreaders, and never top-post" kind of thing was a big part of the appeal. Possibly I could only get read-only access through whatever free provider I found.

At the time, the communities discussing interactive fiction and roguelike games were still centered on usenet (rec.arts.int-fiction and rec.games.roguelikes.* respectively) although iirc half the conversations were on the need to move on, to web forums or whatnot.