I think the time and date stamps come from the e-discovery forensic tools (reading in the metadata into the forensic artifacts.) Melendez testified to that really early on in trial 1, I think it was day 2 or 3.
Well I don't think so because the time and date stamp co-ordinates with exactly the time that she claimed he sent it to her and from the testimony it appears that they were on the front of a picture.
I'm trying to remember technology from back in 2006, remember no smart phones, and very few people had or could afford much more than talk and text plans. Not sure data plans for email were all that popular?
MOO