Class groups are created as announcement-only mailing lists which means only the instructor can send email to the group. If you wish to allow open discussion among students, here's how.
Browse to Google Groups for uni.edu to see a list of the groups you a member of. If you are logged into your UNI Gmail account , you can click on the "Groups" link at the top.
If the URL in the address bar does not specify uni.edu, you are at Google's public group directory which is not maintained by UNI. Browse to http://groups.google.com/a/uni.edu  to be sure you are at UNI's Google Groups page. Also be sure you see your @uni.edu email address as the account signed in at the top right.
- Browse to the list of your Google groups, see the explanation above.
- Click on the class group for which you would like to make changes.
- Click the "Manage" button.
- Click on "Permissions" to dropdown more options, select "Basic permissions".
- Change the "Post" setting to be: "All members of the group"
- Click the "Save" button.