An email you don't use anymore.

I set up an AppleID with an email about 15 years ago. I don't no longer used that email for about five years. I use my current email to sign in. This morning I bought a new imac. While filling in my usual current email on Apple ID. It states that my apple id needs verified. I type in my current email. It does not recognise it. I think it is asking for the ex used email which I don't have access to it anymore.

What can I do?