How Do I Turn Off The New Mail Sound On My iPhone?
Go to the Settings app on your iPhone or iPad and tap on Sounds & Haptics. Swipe down to "New Mail" and tap it. Under Alert Tones you can tap on "None (Default)" at the top of the list. Additionally, you can turn off Vibration by tapping on Vibration, swiping down to "None (Default)" and selecting it. You may also want to turn off other common sounds while in Sounds & Haptics, like the Sent Mail sound or the Lock Sound.