OK, with photos disabled, attachments stripped (as before), an email with an embedded picture comes through with a bounding box where the picture would be, showing the alternate text inside, that would be displayed in a text-only situation. I am using Thunderbird to send the email, and it has an option to embed a picture. If the picture is attached, but not embedded, the link shown basically is an empty page. If the photo is a link whose picture is not attached to the message (hence an ordinary hyperlink), then that link works, no photo is embedded. So I think the combination of no photos with attachments stripped will do it.
Herb Gellis