I just got another email because one of my questions was closed as a duplicate. The mail (screenshot) suggests me to
Select the suggestions that answer your question. Your question will be associated with these links so future visitors can easily find the answer. Your question will be marked as a duplicate and become visible to the public again.
This may be appropriate when the question has close votes, but not when it's already closed (which is when you get this email). Also, "become visible to the public again" – I assume that's only for new users on Stack Overflow?