Each time you receive a new message on your iPad, you'll get a small sound notification.
To disable it:
- Go to Settings > General> Sounds
- In the right pane, next to New Mail move the slider button to turn it off.
This document, titled « iPad - Disable sound notification when receiving new email », is available under the Creative Commons
license. Any copy, reuse, or modification of the content should be sufficiently credited to CCM