I had a similar problem. I moved in with people who had cox. I cancelled mine but kept my email only. Cox created what they called a virtual address for me. It took some effort and I pay $9.99 per month. Don't know if this will work in your case but you could run it past cox customer service.
You would only be able to keep the email addresses temporarily; they are usually deactivated a couple of months after cancelling service to give time to transition over to a different email address if necessary.