With iOS 11 and later, and iPadOS, Automatically is set by default. Your device will fetch new data in the background only when your device is charging and connected to Wi-Fi.
When you are using the mail application, however, new mail will be fetched.
Issue Receiving Email When Using Cellular Data
Another common question/issue is users reporting not receiving any new emails, even while inside the mail application when they are using cellular data. To fix this issue, follow these steps:
- Navigate to “Settings” > “Cellular”
- First, make sure the “Cellular Data” toggle is in the on position
- Next scroll down that screen to where you see which apps are allowed to use Cellular Data
- When you get down to the Mail app, toggle it on if it is in the off position