When you set up a notification on an index and then receive a notification it has a link to view it in the web portal.
Now, when you click on that link you will be taken in as a view only user and can only see messages, trends and regions. You will know you are in view only mode if you see the green bar.
Why is this important? The notification will likely be shared, either the email is forwarded or it is copied / pasted into a ticket.