|If this is a new notebook and still in warranty, then let Tech people at Acer deal with your problem.|
If you want to solve the problem yourself, which is the best way to learn about how to solve computer problems, then look into BIOS for settings that wake up your PC from sleep.
Some of the wake-up options may be, timed wake-up, wake-up by LAN, wake-up by mouse, if you have one, etc.
Also check your LAN card settings in Device Manager. It may trigger wake-up when an e-mail comes to you.
These settings may be under Power Management or Advanced.
Happy new year.