It’s actually impossible to attach pictures, they always are displayed in the mail. Also, when you drop a file into the message it’s not “attached” in a “attachment box” but their icon is actually floating anywhere you dropped it in the message.
If you right-click (two-finger click) on the photo you can toggle "View as icon"/""View in Place". The default is to show it directly.
Well, you can drag them to the end if you want them segregated. Usually I prefer them inline, but sometimes I drag them to the end. I don't know what an "attachment box" is.
Outlook used to get confused -- when it first encountered an attachment it simply ignored the rest of the message. I think MS eventually fixed that bug. Is an "attachment box" an outlook thing? Apple mail correctly finds and handles any attachments anywhere in the message.
RFC 2183 allows for “inline” and “attachment” dispositions. Inline are part of the body and “inline” with the content of the mail and are automatically displayed. Attachments are to be shown as icons or links in a designated area.
