My wife has an iPhone 7+ running IOS 12. Plenty of hard drive space, no memory issues. Once or twice a week she discovers that mail has come in - which she can see if she goes to her macbook or our ipad but which DOES NOT SHOW UP ON HER iPHONE. Mail sent during the day seem to arrive fine. She has no DND or any other restrictions set at night. It just seems that when the phone is sleeping it does not get email and in the morning it doesn’t retrieve it. The other two devices do.
It’s obviously not the carrier or the email vendor. Neither the laptop or the pad are set to delete the mail from the server.
Anyone have any ideas?