By default, pre-fetching is enabled so the app automatically loads new emails in the background, resulting in superior load time for new mail. To disable Message Pre-fetching:
1.Tap the Nav icon at the top left corner of the Nav Bar to display the Navigation Drawer.
2.Tap the Gear icon at the bottom of the Navigation Drawer to bring up Settings.
3. Tap Mail.
4. Under the Data Usage section, tap the Pre-fetch emails box to disable it.