The Gmail Notifier is an application that alerts you when you have new Gmail messages. It displays an icon in your system tray to let you know if you have unread Gmail messages, and shows you their subjects, senders and snippets, all without your having to open a web browser.
The Notifier is in beta. Before you download it, we encourage you to review the system requirements and privacy information.
and after installation it will ask for User ID and Password:
Once credentials set , a tray icon ll appear like below
here we can set browser to open mails from options menu
A sample Notification