I found this description of the methods informative:
https://cyberfraudcentre.com/beware-...om-online-scam

natylou, I did email the hotel. They told me it was a scam, which is what I assumed, and not to worry, that my reservation is intact and safe.

And you are correct that some hotels booked through booking.com do take full payment several weeks before arrival date. So people have to read the email closely. Just don't click on a link that the hacker includes in their email. The hotel in Siena told me they would never ask a guest to click on a link and include their credit card information.

kja, thanks for including this. I've read about half of it because I have to leave now for an appointment. But I will finish as soon as I can. It is very informative.