Tried to attach 3 attachments via drag and drop. When dragging the third attachment I choose to place it in between the first two. Later I mailed the message but the one attachment that was mooved out to the right was not an attachment any more. It was only a picture of an icon.
We have the same problem in a CRM database. Sometimes the attachment becomes a picture. The file is still located in the $file field, but you need spesial skills to retrieve it.