Rated 4 out of 5 stars

4/5 because this still has some americanised spellings, that said, 4/5 is good in my book, it does what its supposed to and The recent update of thunderbird have broken my old british dictionary.

Ubuntu 18.04 - Thunderbird 60.5.1 (64-bit)

This review is for a previous version of the add-on (2.70.1). 

Thank you!

:-)