MailPing is a Firefox extension that checks your GMail and Yahoo Mail accounts for unread messages in your inbox. It also offers one-click access to both services through its widget UI.
How to Install in Thunderbird:
1. Right-click the link below and choose "Save Link As..." to download and save the file to your hard disk.
2. In Mozilla Thunderbird, open Add-ons from the Tools menu.
3. Click the Install button, and locate/select the file you downloaded and click "OK".
- This release introduces compatibility for Firefox versions 4.0+ and shrinks the size of the widget a bit - adding the name of the email provider seemed unnecessary given that their icon is present.