To subscribe, go to https://calmail.berkeley.edu/manage/list/mylists. Login, as if you are going to log into your CalMail account. Then after login, at the very bottom of the page, there is a "Subscribe/Learn about a list" box. Type in "asuc_superb@lists.berkeley.edu" and click "Search". Fill out the form at the next page and click "Subscribe". Follow the rest of the instructions.
To unsubscribe, again go to https://calmail.berkeley.edu/manage/list/mylists. Login, as if you are going to log into your CalMail account. Then after login, find "asuc_superb@lists.berkeley.edu" under your "subscribed to" lists and click it. Toward the middle of the page, check the "Unsubscribe Confirmation" box and click "Unsubscribe".