So I'm running Outlook at work; I've done SOMETHING (but I don't know what) that stopped the little envelope icon from appearing in the system taskbar when I have new mail. I actually find that indicator rather useful; how can I get it back?
Is it possible it's just hidden?
On XP, right-click the taskbar, go to properties, and click "Customize..." in the Notification area group. Find the "You have new unopened items." item and change it to "Always show". I assume the process is similar on other versions of Windows.
If this doesn't do it, check your settings in Outlook (see quicksel's answer).