I tried: I "exported" the "file" that I created, with two trial photos. I tried dragging and dropping the JPEG files from the desktop into the Mail icon. That did NOT work - the image appeared as an embedded picture in the email that I sent to my Dell PC! I tried clicking on the paperclip symbol in a new Mail message. That produced the very same result! Additionally, the image appeard as a "Bitmap" (.bmp) file instead of JPEG format!!!
Have you actually been able to send a photo from iPhoto on your Mac to a PC running Microsoft Windows Outlook? Perhaps your method only works if the recipient has a Mac running Microsoft Works for Mac.
Nope, I conclude that Apple does not cater for sending RAW or JPEG files as attachments so that they can conveniently copied/printed/forwarded by recipients - especially the majority (sensible) Windows PC users.
I am hugely disappointed, perhaps I shoud say disgusted, with the Mac sofware on my, very pretty, new iMac. I was fooled by the clever feature on my new iPad, which embeds photo attachments into a new email message on the iPad, but cleverly and automatically converts my Canon CR2 RAW pictures downloaded from my EOS 5D into JPEG attachments as received by my friends' (Windows) PCs. Why can't tje iPhoto/Mail programs on my iMac not do the same??? How annoyingly frustrating!!!