iMazing is a tool that will display you all incoming eMail messages and allow you to instantly delete these messages with a swipe to right gesture. You can also mark an eMail as read with just a swipe to the left.
You can additionally preview the eMails instantly with a single touch. In this preview screen you have also the option to instantly delete (or mark as read) the message via the swipe gestures (left/west = mark as read | right/east = delete).
With iMazing you're Getting Things Done (GTD) - full stop. And of course the application is fully customizable to your requirements - starting with the option where the the message list should be displayed and ending with the configuration when an incoming email should be marked as read (see screen shots for details).
See the iMazing in action @ YouTube:
** The FREE Version of iMazing will display ONLY the latest eMail **
** YOU need to BUY a License (via In-App Purchase) in order to make use of the full functionality of iMazing (displaying a unlimited number of messages) **
** TOUCH DEVICES ONLY **