Random cautionary anecdote about Thunderbird tabs:

My cat stood on my keyboard and opened an email hundreds of times. This made hundreds of new tabs that would re-open every time I started Thunderbird. As far as I could tell, Thunderbird has no function (yet?) to "Close All Tabs" or "Close All Tabs but this one" and so I just gave up after a while and manually closed them all myself by clicking the [X] one at a time.

If I had known how many there actually were (no real way to tell) I would have written a UI automation script (or extension) to close them all, but instead I spent a good 15 minutes closing the same email again and again. To make matters worse it was actually a very depressing email to boot.