Configure the Notifications area to receive notifications about new posts to your system email.
Go to Discussions.
Select Discussions from the Tool Menu of your site.
Click Notifications.
Choose your notification preference.
Select a notification setting:
When someone posts or replies in any topic: receive a notification about every new post to the Discussions tool.
When someone posts or replies in a conversation where I posted or replied: receive a notification about new posts in discussions that you've participated in.