I had heard of Lisa Jackson's "Richard Windsor" account but it hadn't occurred to me that others would have them. It makes perfect sense when you think about it. I would have one...several actually, I have about a half a dozen now...if I was in one of those positions just from a practicality standpoint so that I could sift through the BS for essential communication. Anyone who is high profile does this...Limbaugh, for instance. But government employees, especially cabinet level, would be putting all sorts of things through them that would be more than a little interesting to oversight committees and they would take on an air of scandal as far as the public is concerned because of the "secret" aspect.
Gaining access to these email accounts is going to be an absolute gold mine for the committees.