Turn off "new email" sound on boot
So, based on the comments above you do need a notification solution.  The obvious one is just to turn off notifications for the email app, or to turn down the volume before you go to bed.  You could also use an app like Tasker to do the latter automatically based on profiles that you set.  For example you can have it mute notifications when plugged in to charge: http://androidforums.com/1207528-post3.html