Versions of Outlook prior to 2003 would put a special icon the Windows desktop.
You could right-click the icon and select Properties for quick access
to the Mail control panel applet.

You can restore this icon when using Outlook 2003 by putting the following
lines into a text file, saving the file with a REG extension and then
double-clicking it to store the information in the Registry.

Windows Registry Editor Version 5.00

[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\Desktop\NameSpace\{00020D75-0000-0000-C000-000000000046}]