email notifications are normally turned off by default. If you wish to be informed of a new post since you last visited the board please go to the User Control Panel (top left hand corner of this page) and set your board preferences as follows:
Many email service providers treat all message board notifications as "spam". If you have set your preferences as shown above and are still not receiving notifications please look in your spam folder to see if they are there.
A handful of email servers simply refuse to accept message board notifications even as spam. The chances of this are only about one in a hundred. If this is the case with your email provider I'm afraid there is nothing you can do short of finding another provider.