Rated 1 out of 5 stars

I would not use such hard word, but I must repeat (in enlgish) that your software looks like pure rubbish. I know what I write. Bear in mind that I'm using Thunderbird from the very beginning (say version 1 or 2). I too wrote software producing my portion of rubbish. You are not alone.
Try to contact a friend that speaks italian and have a translation of my vote.
So long.

This review is for a previous version of the add-on (0.6.1). 

Ok, so you write something knowing that I wouldn't understand it. Then what's the point? If something doesn't work, open an issue on github. If you just don't like it, then why using it and spamming reviews?