I don't think you can change the sound played unless you know what's the file name of this sound (it will probably be something *.wav in the Outlook folder), you can add a different sound file and rename it to become the same as the Outlook file.. If you want to stop the sound from playing:. Choose Tools from the meny, then choose Options.. . in Preferences tab, choose E-mail Options.... press Advanced E-mail Options.... uncheck the "Play a sound"