By default, you will receive an email notification when someone makes a new post. The person posting can exclude their post from this. You may unsubscribe from these notifications by category or by poster: in the menu bar top left you will see an icon representing your Dashboard. Click on this to reveal a menu and select Subscribe2 > Your Subscriptions. Here you can update your preferences.
Member and forum activity
You will receive an email notification whenever a forum or topic that you are subscribed to gets new content. If you do not want these emails, unsubscribe from the forum or topic. Make sure you are subscribed to all the topics that you want to follow.
Additionally you get an email notification for certain other activity on the site, such as when a member sends you a message or there is activity within a group to which you belong.
You can disable (or re-enable) email notifications for various member and forum activity in your User Settings email panel. Pull down on your User Handle to be found in the menu bar top right. Choose Settings -> Email, update your preferences and save the changes. When emails are disabled, you will still get a notification when logged on, but no email will be sent.