How to Make iPhone Mail Keep Less Deleted Mail

It is white. It is bright. It is snow.
You know that, but your camera doesn't. Your camera knows the world to be gray on average. Ruthlessly, gray is what it will make the snow look in your images — if you don't stop it.
To make snow white, overexpose relative to what your camera deems correct: scour the manual for "exposure compensation" and notch up the exposure an EV or even two .
It is old. It is useless. It is your deleted email.
You know that, and so does iPhone Mail. It still keeps the deleted messages for a mighty long time — if you don't stop it:
›› Avoid deleting every message twice. Have iPhone Mail empty the "Trash" folder more frequently instead.