How do I turn off the unread message count on the Windows XP login screen?

For current logged on user:
HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\UnreadMail

For all users on the computer:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\UnreadMail

On the right pane, find a value data named MessageExpiryDays. If it’s not found, create a new DWORD key namedMessageExpiryDays. Set the value of “MessegaExpiryDays” to 0, and save the setting.