Rated 4 out of 5 stars

This fixed a problem I was having with Thunderbird since the latest update. Each time I started Thunderbird, I was getting tabs from an old session. Even though I closed those tabs after the startup, they kept returning with each new startup. So, I installed this add-on and the old tabs stopped opening. It fixed my problem. I don't know if there are any other reasons for this add-on, but it worked for what I needed it to do.