Hi Chhun,
Thank you for the post. In the Services Console (Start > Run > Services.msc), make sure that the AQAServiceManager service is running under the Local System account (see image).
If it's running, but you still don't receive Email Alerts, please open a new case here: https://support.smartbear.com/message/?prod=ALMComplete and provide us with the following info:
1. Can you send a direct email from within the application using the Send Email icon (yellow envelope)? http://screencast.com/t/BH87YJEviWuK
2. Do other users receive Email Alerts from QAComplete?
3. Send us the settings.xml file. It's stored in C:\Program Files (x86)\SmartBear\ServiceManager unless you use a non-default install location.
Anastasia
Customer Care Team