AppleID site asking to verify email address but it's a mac.com email that I am unable to reach
When logging onto icloud.com, I enter my AppleID and password and then I am presented with a message to "Verify your email address" which, in my case, is an old <xxxxxxx>@mac.com address.
The issue is, I am unable to check that email address account. I have seen posts that say it's the same as your @icloud.com account but looking there does not have this "verify email account" email.
If I add my @mac.com email account to iOS Mail, it is either not working or I entered an incorrect password (which is possible since the account is almost 20 years old and I don't know what password I used back then).
Any ideas?