I should add that I mostly don’t blame students for this. It’s evident (and many have said) that they have never been taught this—in English or in Korean—so of course they don’t know how to do it. I have a handout that outlines this. I just usually teach it at semester’s end. —because some semesters, most student email comes in during the grade correction period, and it helps if it’s fresh in their minds that they need to politely identify themselves and clearly explain what they’re writing about.
(Tried to attach my handout but Twitter hates PDFs!)