See the Knowledge Base document on this
subject. Use username@cs.indiana.edu as your "preferred address".
Before you set your preferred email to your CS account, you MUST make sure that
your CS email is not forwarded to your indiana.edu account or you will create a mail
loop and lose email. By default, all new CS accounts are created with a .forward file
that forwards your email to your indiana.edu address. You can just remove this .forward
file to turn off this forwarding and start receiving email locally on the CS server.
You are advised to be sure your CS email is working properly and that you are able
to read it without any trouble before you forward email to your CS account.
Please see the associated FAQ for more information about
email forwarding on the CS systems.