Right click on the photo in the email and select Display as Attachment from the contextual menu. How it ends up is dependent on the email client. You may have it show up as an attachmen before sending and the receiving end may be set to display it in the body.
In either case be sure to set Mail to send Windows Friendly Attachments:
If you compress/zip the file it before adding to the email it will definitely be added as an attachment. But that requires an couple of additonal steps and to assure the zipped file will be Windows friendly you would need to use the free YemuZip application.
I follwed your instructions which I could follow easily. However when I right clicked on the photo in the email it does not give me a choice of dispaly as attachemnet. I only have
Open with Atthachment
Quick Look attachement
Save to Downloads Folder
VIew as Icon
Capture Selection from Screen
It is set at Always Send Windows-Friendly Atttachement
Any other suggestions?
Old Place FL