Click the 9 square button at the top right of the screen.
Click on the Smart PBX app.
Click the User Features field for the desired user.
Click the Voicemail Box feature.
Click the toggle switch for Voicemail to e-mail to disable.
Note: Checkingthe Delete messages checkbox will cause the system to delete voicemails after the email notification is sent, so that new voicemails are not shown on the desk phone.