Apple Mail 10.3: Preference for Spell Check says "Never" BUT IT STILL TRIES TO CORRECT SPELLING, HELP!!!

Can anyone help me disable Spell check (Apple Mail 10.3)? "Never" is selected in the Preferences for Spell Check, and yet the feature continuously corrects and is a total nuisance. I want to spell someone whose name is "Furst" and it insists on changing it to "First".

Any ideas? ?Many thanks for any suggestions or help with this.

gsands@mit.edu