To report Spam in Gmail click the three vertical dots on the right side of the email. Then click "Report Spam" Google will ensure that you will no longer receive emails from this email address as well as protect you from future Spam emails. Screen shots for example are posted below.
A good way to know that an e-mail is fake and not from SJU IT is to please remember that employees of SJU will NEVER ask you to provide your password via e-mail. It is important to take note as to who the message came from.