title: Make a link that opens app if installed, open Google Play/Appstore if not installed, and open another link if desktop pc?
body: <p>I want to make a link in an email, that opens my app, if the app is installed.
  If it isn't installed, I want it to open either google play or Appstore depending on the phone people use.
  If they are on a desktop pc / anything else than android and IOS, it should open another normal weblink.</p>
  
  <p>How is this possible?</p>