I read the manual and I can't find anything on this.

My list is unmoderated and I am using topics to keep it organized
(something the manual does not suggest). Most of the time it works well,
but lately a few people have been using a subject line that starts with the
word ALL: to send their messages. This bypasses the topic system and sends
their messages to everybody on the list. Usually it is an incredibly
trivial message, and twice it has been rude requests to cancel
subscriptions (I did immediately). And then someone answers them with what
should have been a private email and before I know it a whole message
thread is going on. And, yes, I ask them not to use it, but you know
subscribers....

So, is there any way to turn off ALL: as a topic or rename it to something
else like ADMIN?

Thanks for the help,
Karen Strauss