Warning: call_user_func_array() expects parameter 1 to be a valid callback, class 'collapsArch' does not have a method 'enqueue_scripts' in /home/customer/www/allanhutchison.net/public_html/wp-includes/class-wp-hook.php on line 307

Switch dictionaries automatically based on recipients

Also has a how-to for doing it manually.

” … Switching dictionaries manually every time you write in a different language can be quite the nuisance if you have to do so several times a day.
“The Thunderbird extension Automatic Dictionary Switching makes life a lot easier by remembering the selected dictionary for each contact that you have in the browser. It saves the selection that you make under spelling when you are in a compose window so that it will be remembered and automatically selected the next time you write that particular user or users a messages. … “

Source: Ghacks Technology Newsletter
Details  Switch dictionaries automatically based on recipients