I have email notifications turned off on Galaxy S4 and I'm still getting the blue LED indicator every time I receive an email from Gmail. How do I turn that off?
You can use LightFlow to manage all your LED Notifications and use that to turn off LEDs for any programs you want. You can also use it to change notification led colours as well.
You have to just go to Settings > Display > Find here notification light option and disable that.
But keep in mind that all notification light will be turned off, except during charging the phone and low battery indication.