Right-clicking on the photo doesn't allow them to save it? How about drag and drop to Windows Explorer?
I don't have access to my friend's PC right now but here's what I remember.
I can't recall if right-clicking brings up the 'save attachment' option, but certainly when you click the icon in the ribbon bar to do so you end up with an empty list. Quite simply there are no attachments to save.
I'm not convinced that a drag and drop saves the original image with metadata intact. One thing I do know, however, is that my client isn't going to do that for each of the twenty odd pictures attached.
As far as she's concerned this is my problem, everyone else send attachments of all types in a format she can save easily. As far as I'm concerned its Apple's usual arrogant 'we know what's best for you' attitude. Its an issue that's been ongoing for years, both the Microsoft and Apple support forums are full of people like me tearing their hair out over this. There used to be a Mail plugin which solved the problem but every time Apple updated the OS it broke. The developer eventually gave up. There is currently another plugin which works fine for Mail under macOS 10.13, but guess what happens with 10.14.4.
I have been using PowerMail but that's 32 bit and won't be updated. My perfect solution would be for PM to work with a modern compliant email app such as Airmail. Please!
Thanks
David