Mozilla Labs: Contacts is a Thunderbird and Firefox extension that adds a database with your contacts, allowing you to search through them or use the information in emails.
Mozilla Labs: Contacts is an open source add-on designed to work with Mozilla Firefox 3.6 - 4.0 Beta 8 Pre and Mozilla Thunderbird 3.1Beta 2 Pre - 3.3 Alpha 2 Pre.
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".