Block facebook seen notifications, because seen notifications make snail mail a lot more tempting.
First you must install GreaseMonkey for Mozilla Firefox. Then navigate to this link: SeenBlock.
Your browser should prompt you about installing SeenBlock.
On this dialog click "Install".
First you must install TamperMonkey for Google Chrome. Then navigate to this link: SeenBlock.
Your browser should prompt you about installing SeenBlock.
On this tab click "Install".