Messages are bouncing back to the sender saying no such address exists.
You may have mis-typed when you entered your forwarding email address. Go to the mail.case.edu page to check where your mail is going to. Click on options, click on 'mail administrator' and log in again to get into your account information. Your forwarding address will be listed under 'mail delivery options'. Failing that, try 'reset my mail to the default' and start over again. Double check that you have the correct full email address.