For more information about Discussion Forums, you can look through the information bellow or read Moodle's Support documentation
Creating an online discussion is a great way to continue learning outside the classroom. To create an online discussion, we can use the Forum activity.
If you are subscribed to a forum, you will be notified by email of every subsequent post to that forum. These emails allow you to stay informed when new posts are added. Depending on the number of responses to the forum, this could quickly fill up your mailbox. Fortunately, people can usually decide whether or not to be subscribed to a forum, unless the instructor chooses to force the subscription (see item below for how to unsubscribe from a forum).
Faculty can choose if the subscription to a Discussion Forum is Forced, Optional, Auto-subscribed, or disabled. Forced subscriptions prevent users from unsubscribing.
To change the Subscription Setting:
To unsubscribe from a forum:
In Moodle you can set up a Forum to be graded. This is done slightly differently than other grade items.