I've discovered what looks like computer-generated email addresses have been used to sign up to the Jetpack-inspired mailinglist. So far, I've had nearly 400 added and all have the same format of mailing address: <email@example.com>
Apparently, Jetpack only checks that the format of the email address is 'legal' but doesn't actually check if it exists. I've checked a number at random and they're all fake. But why sign up if the list is never going to get delivered, unless it's part of some other, devious objective? (I had a serious DDoS attack a week or so ago that went on for several days.)
So, firstly, how do I delete them? I've already had to remove the Email widget and move back to using my old Feedburner link. And why doesn't Jetpack check that it's a real address?