If you receive an email with a photo attachment, you save that then right click the properties and go to the details tab, is the date associated with its creation the true creation date?
My folks have a court case coming up and part of the argument hinges on whether they had an invoice in their possession or not at a particular date. The other side sent them an email on a date about one week later showing the invoice attached in his invoice book. When I saved the photo and checked its details it stated the photo was taken about 5 minutes before that email was received. One week after he claimed the receipt was given to my folks.
I don't know however if I'm interpreting information incorrectly or whether that is proof of any sort.