All right, I have a much more practical solution. I have noticed this issue, and I agree with Taviman that the sensitivity issue seems present all the time. But if you know how to navigate, the sensitivity is actually more of a feature than a bug.

Here's the secret: when you get to a wide email and need to swipe to see the far side of the email, but don't want to accidentally go to the next email, then (1) put your finger on the N9, (2) swipe horizontally to reveal the side you couldn't see, and (3) WITHOUT LIFTING YOUR FINGER, swipe downward, so that your finger traces sort of a sideways “L” shape. The downward part of this advanced swipe only needs to be a short one-inch type move. This way, the email will not advance to the next email, but stay on the one you are reading. This is my preferred way, but . . .

You can also pan over to the far edge of a wide email by VERY gently swiping near the center of the screen and it will scroll over and stop. You have to have some skill to do this, sort of like finding the 'G' spot of the N9. Soon, you will be navigating between emails and within emails as you like.