Does he address her as "Dear Emma" or "Dear Marianne" or "Dear Sarah", thereby buying into the modern cult of familiarity and casual first-name use?
Or does he submit to using that awful salutation, "Ms."? A word that even sounds uncomfortable and awkward?
There's just no winning this one. But I've taken to choosing the first option as the lesser evil.
(I'm quite pleased by the amount of students who choose "Miss" as their title when they register. What a bright, friendly, euphonic word! But unfortunately most people leave that field blank.)