To notify of new email message the color of tray icon is changed. But with current version we can't get the Thunderbird inbuilt new email notification system.
Note: This release has the unfortunate side-effect of disabling the new Thunderbird 2.0 feature of popping up an alert box for incoming mail. Currently it's impossible to have both my extension and this feature working together. In future versions, this is fixed. In this version, you can always restore the alert box feature by disabling or uninstalling this extension.
I like this plugin better as there is no compatibility problem with inbuilt new email notification system The tray icon changes to number of unread email messages. You have got option to "minimize on close". Custom icon support. Options like create new email message on pop-up menu and so on.
To get either of this in your Thunderbird,
- download it from the site mentioned above.
- Open Thunderbird
- Go to Tools -> Add-ons
- Click install
- Select the add-on you downloaded.