Letterboxing.org staff:

Due to the growing pains you are having, it seems that the best thing to
do is to move towards a web-based discussion forum. That way you could
spread topics around to specific categories, but keep the cohesion of
discussions in one location on the web.

Don't get me wrong. An email discussion group is great but once it
achieves a certain number of users, the system tends to break down.

I'm just offering a suggestion from experience that you can feel free to
digest or discard. I haven't looked recently, but there are various
companies that supply free forums applications you can use without much
difficulty.

Jeremy