Fetch New Data is a feature that allows the user to select how often the device checks for new email. Push is a feature that is available with certain email accounts that automatically pushes email to the device.
Enabling Push requires more power and may effect battery life.
From the Home screen, navigate: Settings > Mail, Contacts, Calendars.
Tap Fetch New Data.
Tap the Push switch to turn on or off .
Select an email account.
Select the schedule option then tap Back (upper-left).
The schedule option is selected when a check mark is present.
Select the Fetch setting.
Selected when a check mark is present.