Imagine a tiny boat afloat on a thrashing sea, water pouring through a gaping hole in the hull.
A sailor is frantically bailing dark, angry water, but no matter how much he scoops, the water line never seems to recede -- more waves just pummel him in the face like a particularly insecure middle-school bully.
That, my friends, is our metaphor for the average worker's e-mail inbox....