Is it the norm for hotels in Athens(The New Hotel) and on Santorini to request full payment 8 months in advance.
I was required to make full payment for a hotel stay in Athens 5 months in advance. I did it but I used a credit card which I sent in 3 e-mails. Don't know if that is any safer than just sending it in one e-mail but I probably should have called them.
It's not all that unusual, but if they ask for a bank wire transfer you will pay hell getting your money back if you cancel. If they won't take a credit card or if they don't have a reasonable cancellation policy offering a full refund within a reasonable length of time, look elsewhere.
In 11 trips, I very seldom have had to pay even a small deposit, but I stay in modest lodgings. It sounds as if these are luxe hotels in Athens and Oia -- places that are very "in" for top-drawer travelers -- and so they can get away with it. Agree with Lee, if they don't have a reasonable cancellation/refund policy, would look elsewhere.