The message count has reached more than 284030 messages! Almost 5000 posts in January alone...
Unfortunately, Yahoo deletes older messages, so anything before March 2003 is no more accessible.
So, if you believe that your contributions should be preserved for more than a couple of months, Global Affairs at MSN might appeal more to you.
On the other hand, at Yahoo, there's a new message every few seconds - a very active group indeed!