You can't do anything with a photo that's embedded in the email. Just save the email and use the client on the desktop to copy. If it's an attachment then click the 'download' link, once downloaded right click the thumbnail and select 'save'. The app screen opens where you can select where to save. I usually select desktop.
Surface Pro 4 UK release date, price and specs: Thinner, lighter, faster with new Type Cover and Pen