My personal email inbox has these three messages in it.
One is from a piece of hardware in my house (Twine) whining about dying. Another is from a piece of software in ether reminding me to mess with another piece of hardware in my house (my Nespresso machine). The final one is from my climate control system complaining that the air filter needs to be replaced.
Awesome examples of engaging emails that will get me to act, and make my life better/easier. I'm sidestepping the "nag" factor for now.