Richard J. Hughes
Please leave this option set at the default, thread-specific e-mail notification, when you register. This will send you e-mail whenever someone adds a message to a thread to which you have already contributed a message.
If you change the e-mail notification option to all messages, you will receive e-mail whenever anyone posts a message in any of the boards in that session. We chose to enable registration on a per session basis so that you didn't need to register separately for each board.