How To Move Stuck Email from Any Folder to Trash Folder in iPhone/iPAD

I tested this successfully for couple of times and it works:-

1) Put the iPhone in Airplane mode

2) Open the Mail app

3) Go to the Outbox

4) Click Edit, click the circle next to the stuck message to select it

5) Click Delete

6) Take the iPhone out of Airplane mode

7) Return to the Mail app. :-)