But, the reason for classifying it Confidential is a standing criteria. It was most likely considered Confidential at inception.
If Clinton (and the rest of her staff) had paid attention during their security briefing/indoctrination, they would have known that.
Yep. Nice weasel word. Note that if it was classified at inception then it was also classified after it was sent. Thus, AP can say it was 'classified later'. It was also 'classified earlier, like at inception.