Moodle has several features to support instructor-to-student communication as well as student-to-student and student-to-instructor communication.
Every Moodle site contains an announcements forum, which provides a one-way means of communication for the instructor to send out messages to the entire class. Anything posted to the announcements forum will be sent to the entire class as an email. Past messages can be viewed by clicking into the forum.
The announcements forum is tied to the "latest news" block in that any announcement posted to the forum will appear in the latest news block. If you ever accidentally delete your announcements forum, you can add it back in by adding in the lastest news block.
Adding a forum to your Moodle site provides a means for students to share work and discuss information with each other, as well as post comments or questions for the instructor. Moodle has different forum formats that lend themselves to different kinds of activities. Forums have subscription options which allow users to decide if they want to receive emails of each forum post, or not.
Emailing through Moodle