I have sounds turned off for my Outlook desktop client because I don’t like the interruption for my train of thought. Recently, I was working in the web version and couldn’t figure out where to turn the sounds for new mail off in Outlook Web App. I looked in options for OWA – but it wasn’t there.
After a little more tinkering – it’s actually in Office 365 Settings.
From here – go to notifications to set your notifications for mail and calendar reminders.
I have mine set to show the notification – but not to play the sound. Finally some peace and quiet!