Disabling notifications per Account Settings | Notifications does not seem work on Windows 10. See my settings:
I am able to disable the text part of the notification by configuring system notifications (unable to post more than one image because I am a new user, so no screenshot for this…) and I’ve also tried just disabling desktop notifications entirely (setting “Send desktop notifications” to “never”) but the sound still plays no matter what. Mattermost does not show up in the Windows volume mixer so you cannot disable it there either.
It’s driving a couple of my users crazy. The only way I can find to disable sounds in the native Windows client on Windows 10 is to mute speakers.