How can I send jpgs to Windows users and have them not embed? Sending as windows-friendly does no good.

When I email jpgs to Windows users, the jpg always embeds in the message. Why is this and how do I stop that from happening? The Windows users some times send the jpg from their computer to their phone, and can then retrieve the attachment, and send back to their computer.

Sending as "Windows friendly attachments" makes no difference. I don't see any settings to change . . .

Thoughts very much appreciated!