Commas

Q. I seem to be alone in my habit of including a comma in email greetings that begin with a salutation (e.g., “Hi, Mom!”). Most people, perhaps inspired by the more formal “Dear Mom,” seem to think it should be without comma. What do you think?

A. You are right: in formal writing, direct address takes a comma before the person’s name. One could argue, however, that email isn’t formal, and that there’s little harm in streamlining for the sake of efficiency—and I think I can speak for moms everywhere in saying that we’ll take whatever we get in this regard.

[This answer relies on the 17th edition of CMOS (2017) unless otherwise noted.]