Rated 4 out of 5 stars

This is just what I've been looking for! I'm using it to sync Thunderbird's address book to a Kolab server and it is working just fine. A couple of weeks in and everything is running smoothly. I've previously used SyncKolab, but found that had a tendency to produce some nasty surprises, but tzpush seems to do pretty much exactly what it should. One slight niggle is that the second line of addresses isn't transferred, but on the plus side it seems to be being actively developed and all the niggles I've identified so far have been quickly resolved. A really useful addon!

This review is for a previous version of the add-on (1.2). 

Fix for this issue. see https://code.google.com/p/tz-push/
Or wait and will be here very soon
Mark