he first thing to do is installing gContactSync. Before that can be accomplished, download the necessary file from the gContactSync site. Once you have that file downloaded, open Thunderbird and click the menu button. From the Thunderbird menu, click Add-ons. In the Add-ons window, click the gear-icon and select Install Add-on From File (Figure A).
Figure A: Installing an Add-on from a file.
Locate the downloaded file, select OK (or Open—depending on your platform), and (when prompted) click Install Now (Figure B).
Figure B: Almost finished with the installation.
To finish up the installation, restart Thunderbird. When it re-opens, the gContactsSync wizard will launch (Figure C).
Figure C: The gContactsSync wizard.
Select Use a New Account and then type your Gmail address. Click Next, and you will be greeted by the tried and true Google login (Figure D).
Figure D: The ol' Google login window is ready.
Once you authenticate your Google account, you will be presented with the gContactSync Settings window (Figure E), where you can select the Address Book and the Groups/Contacts to synchronize, as well as select the direction for synchronization.
Figure E: The gContactSync Settings window.
I recommend checking the box for Skip contacts without an e-mail address, as your Google Contacts most likely contains a number of people who have no associated email address. There's no reason to add those people, as you won't be emailing them without an address.
Once completed, you should see your new Gmail contacts in the Thunderbird Address Book.
And that's all there is to syncing your Thunderbird Address Book with your Gmail Contacts. As an added bonus, if you configure the add-on to do bi-directional syncing, any contact you add to that Thunderbird address book will automatically sync with Google Contacts. That's a win-win for keeping your email efficient.
