Something I've seen quite a bit of while reviewing Low Quality Posts: obviously incorrect/irrelevant answers. (Case in point: this answer.)
What is the recommended approach to this? The answer is almost two years old and the answerer isn't even a member of Ask Different (so they're not likely to come back and fix it). I fixed the grammar (which wasn't [relatively] all that bad to begin with), and noted that it was completely irrelevant (it referenced Messages, not Mail) in a comment.
What is the "best" option in the review options? It doesn't "Look Good": it's crap; it doesn't need editing (anymore); and I'd like to delete it, but I'm not sure "utterly irrelevant" is a good reason to delete an answer.