I've seen these before also. Thank goodness our ISP spam filter catches them before they get to us. These aren't important enough to me to worry about reporting them, but I do report the ones I get for ebay, Pay Pal, and our charge card.
I've deleted the aforementioned and have had no trouble after doing so. We received one concerning our charge and I called the service center, number is on the back of the card, and had them check our account. They also were kind enough to give me their fraud e-mail address.
Any time you receive something which says your account will be cut off, or you owe money and you don't have an account or owe money, delete them or report them. And if you get something stating it's from your bank, call your bank.
If something gets your goat, it just proves you have a goat to get.