Disabling Outlook 2003 Email Alert Pop-ups

Can you tell me how to prevent Outlook 2003 from popping up an alert from the Windows system tray when a new email message arrives? I know how to disable alerts manually on each machine, but I'd like to turn off pop-ups for a group of users all at once.

The Outlk11.adm administrative template provides a Group Policy setting to manage that option. Open Group Policy Editor (GPE) and navigate to User Configuration, Administrator Templates, Tools, Options, Preferences, E-mail options, Advanced E-mail options, Desktop Alert. The Check to disable New Mail Desktop Alert policy setting controls the NewmailDesktopAlerts DWORD registry value at HKEY_CURRENT_USERSoftwarePoliciesMicrosoftOffice11.0OutlookPreferences. The default value data (0) enables alerts. To disable alerts, change the value data to 1.