An email from Tesla? Never heard of that. In five years of owning Model S the updates have all been announced on the screen (with options of set time to install, or install now) and most have been accompanied by an iPhone notification from the app that an update is available. Note that when your car says an update is available, it has already been downloaded, you just need to install it. Stay away from the car when it installs. Don’t be tempted to “check on it”.