OUCH! I worked the bulk of my professional life in environments where a miscue like that could easily have earned me a 25 year vacation, so I understand.
I may have a workaround that might reduce the risk. Assuming you address the emails by name and Mail fills in the full name and email address. Edit the entry for the person you do not like to add a stray character to his name. So Instead of JoeA it becomes ".JoeA". The dot or period is easily overlooked by the recipient and unlikely to be the first character in someone's name on your end. Hope that helps.
That is an old standby to force an item to the head of an alphabetical list. CAUTION: File or folder names beginning with "." makes them invisible on a Mac so tilde (~) or double square brackets ( [] ) are frequently used in that situation.
