Rated 5 out of 5 stars

I find this plugin excellent but there is one behavior I would modify: when I write to multiple people, I would want the language information to be saved for the group of people and not for each people individually. My language choice changes whether I write to someone in a multi-people email or in a one person email.

This review is for a previous version of the add-on (1.8.1). 

Hi! I'm glad you like it!
It only stores the language to the people individually if it has never saved for them. Once you have your people individually and set the language, it will not be overwritten.

Anyway, If this does not work for you, feel free to send an issue here:
https://github.com/beltrachi/automatic_dictionary/issues/new