Something like Electron which allows you to create cross platform software using JS. I know, I know, JS to create a win 10 app? Yup, it's probably the easiest way right now. There are many email related apps that use Electron, maybe they can help you decide if the framework is right for you: https://www.electronjs.org/apps?q=email
As for which editor/IDE to use, Visual Studio Code is a decent and free text editor with tons of plugins. Then there's always a proper IDE like Webstorm by JetBrains that offers much more functionality and convience out of the box.