Whose fault is it when our messages go viral? The problem is that we assume email is essentially like speech. Unless there are snoops eavesdropping, we proceed as if what we say in private, stays private. We forget that email isn't speech, yet we have come to rely on those short written messages as if they were.
If you were Vladimir Putin, or President Xi of China, what would you do if you had the entire archive of Hillary Clinton's emails, classified and unclassified, "deleted" and not, in your hands? What value to you would that be in your next round of negotiations with the president of the United States?