Rated 5 out of 5 stars

I was led to Cardbook because I wanted an add-on that would sync address books with Google. Rather than just syncing address books, however, Cardbook is a feature-laden independent address book for Thunderbird. It integrates fully with Thunderbird, but it is accessed through a separate tab and operates independently of the regular TB address books. I like the way it presents the contact information and meets vcf standards. It also has many features such as eliminating duplicates, copying contacts between address books, finding emails linked with a given contact, and more. The only thing that I missed initially is the search function, which searches all fields. However, there is a simple way to create a temporary virtual address book by searching specific fields that provides the search functionality I am looking for. Setting up and linking to address books from many sources is easy, and you can import the existing TB address books, also.

The author is extremely responsive and diligent. I had a problem with my Google account syncing getting locked into a loop. He provided me with special versions to gather data. After some work, he tracked the issue to Google responding to sync commands in a strange way, and he created a fix for the issue in a new version. Based on my experience, I expect this add-on to be maintained and advanced regularly -- which gives me confidence to depend on it for a long time. Highly recommended!

This review is for a previous version of the add-on (60.2).