With the reading pane on the right, keep the inbox list from moving when incoming messages arrive
When reading email and a surge arrives, the inbox list will jump and move around. This can cause the focused message to fall off the screen. If one isn't careful, an errant mouse click will delete the wrong message.
I've had messages arrive just as I'm clicking, causing the list to scroll and me to click on deleting a different message than the one I'm viewing.