This is just a suggestion for when/if the message boards are upgraded (not a complaint!!)
It sometimes is a problem when spam infiltrates a thread or guests randomly post "bumps". Also, when guests post but their messages get lost because they sometimes end up further up the thread by the time they are approved.
Would it be possible to treat posts by guests and logged-in members differently? Logged-in posters will have their posts go directly up to the thread (as they do now) but guest posts go into a "queue" where they don't actually posted to the thread until a moderator approves them. Also show a message at that point that explains that the post will be put up to the thread after it is approved, and that signing in will speed the process and save volunteers' time. This would eliminate spam interference, gratuitous "bumping" and also only insert guests' posts into the threads when they are visible to read.
Kate