You would have to setup the power plan a certain way.
If you close the screen on laptops they will just suspend everything, which means you wont get emails or sounds.
If you set it up so the screen turns off when you close the lid and put it on power saving (might as well) than it will do as you want it to.
BTW since you plan on leaving it on overnight, once you fully charge the battery remove it from the netbook and let it run on AC power. If you leave the battery in with the ac adapter in the battery will degrade faster than normal, it wont be a huge difference but a noticeable one. Then in the morning if you need to take it somewhere, put the battery back in and take it wherever.