Apple recently published a technical note about a problem saving photos from Mail to iPhoto in Mountain Lion. I actually came across this problem recently, and there was no feedback suggesting that the photos were not saved. Fortunately, I had a Time Machine backup of the email containing photos in question.
The fix is simply this: launch iPhoto, then drag the photos - one by one - from the e-mail onto the iPhoto icon in the Dock.
Mac OS X Hints
http://hints.macworld.com/article.php?story=20121011005348476