It could be possible to add possibility to remove already included installed languages from spell check?
It is time consuming when you spellchecker the mail and you need to change spellcheck`s language - you have to move thru 16+ languages.
spellcheck is already implemented. When you are composing new email (New Message window) Tools - Spellcheck language - select which one you want to use (or download).
You can switch between them so you will have always turned one on and rest off, this way you can achieve your requested feature