Keep in mind that Usenet isn't really a "messageboard" in the sense that this place is a messageboard. It's an entirely different type of animal from the web. Even though most of its newsgroups (with archives) can be accessed through Google Groups at the link provided above, it'll seem a bit different if you're used to this place.
As for some of the older messages at JMSNews... Genie is now defunct, and while Compuserve's SFMedia Forum is still running, JMS hasn't been spotted there in quite a while. We think he's abandoned us.
As stated above, it is not a messageboard at all but a "Usenet" newsgroup - perhaps the precursors of message boards in many ways. The newsgroups are available on most (not all) ISPs, and you need to subscribe (free) through your e-mail client to read them. Outlook Express actually handles news account pretty well, if your ISP has them.
The primary one used by JMSNews (for B5 stuff) is
However, they are also now archiving material from
as well to pick up any comments he makes there about his comics work for Marvel.
Because JMSNews only picks up JMS' own posts, I very occasionally stop by rastbm itself if he appears to have responded to an interesting, meaty post from someone else, but for the most part I can take it or leave it.
Back in the dim and distant past of 1998 though (before messageboards on the whole) I used to hang out a lot in the alt.babylon5.uk newsgroup which, like this board, had some extremely knowledgeable and interesting people posting - but not JMS.
Must remember to have a look at some point and see if it is still going.