You may want to get a task killer.. check in the market I like "advanced task killer" its free and in the market because My email app runs in the background of my lg optimus t and gmail as well but I also have a task killer to end it after I finish checking my mail to save battery power because my phone is my mp3 player as well.
If the phone continues to over heat call up customer service and get it swapped out my old blackberry started burning because of over heating issues.. Not fun at all
Hope I helped.
"Art enables us to find ourselves and lose ourselves at the same time. ." - Thomas Merton
Facebook me, lustandfatalwine