The Message Viewer link will only work if it is clicked from within a live message or a test message. The message Viewer link relies on encoding that occurs when the message is processing for delivery. The encoded Message Viewer URL is a unique string of characters that correlates with the email message that was sent from Luminate Online. This allows our emails to use a static URL for the Message Viewer link within a Stationery that can be used with any email message sent from Luminate Online.