By default, Outlook has the Desktop Alerts feature turned on - when you receive a new email, a little box appears in the lower right corner of your screen with the name of the sender, the subject, and the first 2 lines of the email. If you don't want these alerts to appear, you can turn them off.
Outlook 2003 & 2007
- In Outlook, go to the Tools menu and select Options.
- On the Preferences tab, click E-mail Options.
- Click Advanced E-mail Options.
- Uncheck Display a New Mail Desktop Alert.
- Click OK 3 times to close all windows.