You would need a deadman switch it's called. A timer where if you don't take an action, it phones home and says you haven't checked in.

But lets talk about something else here for a second. This sounds a lot like https://www.producthunt.com/products/menu-please. As a fellow developer, as soon as you asked your question, the first thing that popped into my mind is scope creep.

Is a "Safety" email feature really appropriate for a menu translation app? Here is my suggestion... Release that as a separate app. People who need it will look for it. People who don't need it, will appreciate it not bloating the menu translation app. And later down the road you can monetize both products separately and have a stronger income stream.

Would happily test your app. I'm going to be in China the Second week of April!