Google does not provide a Gmail notifier in Linux. Fortunately, there is CheckGmail, an alternative Gmail Notifier for Linux systems. It is fast, secure and uses minimal bandwidth via the use of Atom feeds. CheckGmail is a system tray application that checks a Gmail account for new mail.
When new mail is present the tray icon changes, an optional animated popup is displayed and a tooltip displays the number and details of new messages. Each message can be opened directly in a browser window, and many common Gmail operations (marking as read, archiving, deleting or reporting as spam) can be carried out on messages directly within CheckGmail, without the need to use the Gmail web interface.
If you are using Ubuntu, a simple command-line of “apt-get install checkgmail” will install the application for you. Start the application. Edit the CheckGmail Preferences. Enter your Gmail account and password. You are good to go.