Why?
Bad things happen. Sometimes, they happen to you. If something does happen, you might wish there was something you had told the people around you. How you feel, what you regret, where the money is stashed.
For this, you need a dead man’s switch.
How?
This is how this works. You write a few e-mails and choose the recipients. These emails are stored securely, so you can be sure that no-one except the intended recipient will ever read them. Your switch will email you every so often, asking you to show that you are fine by clicking a link. If something were to… happen… to you, your switch would then send the emails you wrote to the recipients you specified. Sort of an «electronic will», one could say.