optonline mail

I was told that when I moved and opened my own Optimum account I could keep my previous optonline email address and all my past folders, contacts, etc. I could not set up the email on my Mac or my Windows 10 PC. When I called support, they said they no longer support emails and had deleted my account! Strangely, my mail does show up on my iphone, and is fully functional. WTH?

Does anyone know why the account is still functional on my phone? Is there anything I can do to access my emails from either computer without losing what I still have on my phone. Totally confused, but would like to not lose my old emails.