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!