Offline Email Notifications

Hello,
I have a small problem with some users, on the server

Accounts > Default User Preferences > Offline Email Notifications

I have set option Disabled and most users inherited this preference but some not, how can I force this change to be applied to them? They send unnecessary emails that somebody wrote something on the chat. All users use Desktop Application.

If you are looking to force it and are comfortable with mongo you could force the setting on all users

That is right, I would like to force the setting on all users but I’m not comfortable with mongo.
Could you tell me how do this?