Set iPhone to only fetch mail manually
In older operating systems (can't remember last one - now using iOS 11.2.1) you used to be able to turn off push in the Mail settings and set it to fetch either at your chosen interval or manually. Is this still possible? My phone seems to be able to download mail when the Mail app is not running (i.e. swiped up to quit) and the phone asleep. I don't want it to! I'm using POP mail.