The first time most people hit an outside the post shot, also known as ‘around the post’ or ‘ATP’ shot, is in a defensive situation. They have been driven so far off the court, generally to the right hand side if they are right handers, that when they return the ball, it travels outside the post that holds up the net. This is perfectly legal. In fact, it is legal even if the ball doesn’t go as high as would have been necessary to clear the net. If you’ve returned a ball outside the post at least once, congratulations! Having done that puts you in an elete class!
Now, let’s take it a step further. There in a situation in which you can return the ball outside the post as an offensive maneuver. This happens in a diagonal dinking rally. Let’s say you and an opponent have been dinking diagonally and it is becoming quite extreme. At some point, you can let the ball bounce as you move well to your right – assuming you are right-handed – and you can let the ball fall from the bounce quite close to the ground. Literally inches above the ground. By the time it falls this low, it has also moved well past the right sideline. You can hit it low and long to the back corner, just back inside the sideline, and there’s just no way the opponent can get it back.
Here is a demonstration by Brian Staub for Poach PB: