Yes, but we’re trying to emphasize that while re does mean “regarding”, it does not come from “regarding” and is not an abbreviation.
Of course, in practice these days, most mail programs have a Subject: line, not a Re: line; most mail programs prepend Re: to the existing contents of the subject line when replying to a message. This has probably added to the confusion, associating Re: with “reply” or “response.” Many of my clients have told me with great aplomb that it means “reply” or “response” or “regarding,” and nobody ever believes me when I say it’s actually from Latin.