Rated 3 out of 5 stars

per Crits el mar. 8, 2012 ·

Very useful, and almost transparent.
I would have given this add-on 5 stars if it wouldn't make my Thunderbird v10 crashed around 10-20% of the time.
Languages used: fr ("built-in" Thunderbird) and en-US ("United States English Spellchecker" module)

This review is for a previous version of the add-on (1.3.2.1-signed.1-signed).