**Don't send the email**. English-shaming is no better than fat-shaming or any other type of shaming, and no more likely to cause a person who behaves in ways that aren't necessarily ideal for them to change their behavior, but on the other hand is quite likely to cause negative feelings such as guilt, self-loathing, low self-esteem, depression, etc., that will likely make that person's situation only worse than it already is.

There is a time and a place to offer people negative feedback that might help them improve, e.g., when such feedback is directly solicited from you or when you are a person whose job it is to offer such feedback. That time and place is not your current situation. So don't.