When I insert an image into the body of an email it shows up as an attachment?
When you paste an inline image it will normally show also as an attachment “in the sent folder”, but (won’t normally show at the receiving end) as in my example post below in the following thread with eg: .png images pasted inline.
So if your inline images are still showing as attachments “at the receiving end”, then could be to do with your eg: specific images / image types, or could be the receiving mail client compatible.