Lost email settings and no icon for Mail I've lost my Settings → Mail, Contacts, and Calendars on my iPhone 5.  No icon for Mail and no Mail settings.  How do I get it back?
On iOS 10 you can delete stock apps. If you accidentally deleted your Mail app, to get it back, you have to search it on the App Store and reinstall.  

They are not actually deleted though, just hidden, so you won't be downloading anything.