The News forum appears by default in the ‘topic 0’ section of your Moodle site. It is useful for making general announcements as all users enrolled on a course are subscribed to the forum automatically, and they should receive an e-mail with a copy of any post to the forum (depending on how they have set up their profile settings).
However, even though students are not able to start a new discussion topic in the News forum, by default they can reply to posts. This would also send a message to all enrolled users (again, depending the profile settings chosen by individuals users). To avoid e-mail overload, especially if there are hundreds of students enrolled on your course, you may want to stop students being able to reply to News forum posts. This screencast explains how: