Rated 5 out of 5 stars

Best implementation of CardDAV/vcard (i.e. using with a SOGo server backend in our situation). Very active and responsive developer.
Would love for this to be the standard Thunderbird address book!

This review is for a previous version of the add-on (56.9). 

Rated 5 out of 5 stars

An excellent address book replacement tool with much more functionality. Perfect integration with CalDav & CardDav backends (we use SOGo & Nextcloud).
A very active and responsive maintainer. A perfect example of a quality add on.
Ha, I just realised that I wrote a review already in former times (I wondered). It deserves it :-)

This review is for a previous version of the add-on (43.0). 

Rated 5 out of 5 stars

Excellent management of all your contacts and their CardDAV integration. We use it with SOGo and it never missed a beat.
Great, ongoing development and support.

This review is for a previous version of the add-on (25.1). 

Rated 5 out of 5 stars

Using this add-on with Thunderbird on Linux client (Ubuntu) for several months now successfully with Sogo as the backend.
As much as I love what the Sogo solution offers, the Sogo connector was not always 100%.
This add-on has is doing a great job and I have not had any issue. There are still features that I need to understand better to fully utilize (i.e. expected date format [for Sogo], the priority how email addresses are shown) but I just need to find documentation to sort these.
A big Thank You to Philippe for this development!

This review is for a previous version of the add-on (21.5).