Florence,Italy accommodation

Googling does not turn up an official website for this property, so you'll probably have to e-mail them directly.

Trouble is I cannot find a valid email address

You can try booking.com to search for the hotel by name, then go to the property info page and there should be contact info for the hotel, if they are listed with booking.com. You won't need to reserve through them.

Here's an old thread with the same question, it mentions a travel site but that gives only the phone number! We loved Soggiorno Battistero, btw, just a few blocks away.
https://community.ricksteves.com/travel-forum/italy/hotel-casa-rabatti-florence

We don't have an updated email address for Casa Rabatti. You could also try calling 011-39-055-212-393 and keeping your request very simple (or in Italian).