Rated 5 out of 5 stars

It just works. It's simple to install and configure. I've been using it for 6 months: email and calendar both sync perfectly.

I had been using Hiri for a few years and had repeated problems with it getting broken every month or two and having to reinstall or remove my account and set it up again from scratch.

I have zero problems with Thunderbird and OWL: it's completely stable and has far more capabilities and a better UI than Hiri did.

This review is for a previous version of the add-on (0.8.3).