If you need to easily see when a new message arrives, even from across the room, you can set up a rule to pop up a dialog box on the screen.

Like all rules, you can set conditions so it only applies to specific messages or apply it to all messages.

Go to Tools, Rules & Alerts and choose Create a new blank rule - no conditions if you want it to apply to all messages - then choose the next to last action - display a specific message.