Do you really need an example? I have no idea what’s in those emails, but it isn’t impossible that something could be really damaging to Hillary while not originating on her server. For example:
From: Huma
To: Hillary
Subject: Disposal of sensitive data
Hi, Hill. Just wanted to let you know that Sidney took care of those ‘extra’ emails, and we are assured that there will be no way to tell that the messages were scrubbed after the subpoena date…
Heck, they don’t even have to be sent to Hillary to be a problem. A letter from Huma to Sidney Blumenthal asking that he make sure that records were wiped properly could do it.
Of course, none of us have any idea. This could be a big deal, or nothing. My intuition tells me that if this looked innocuous the FBI would not risk making a big deal out of it right before an election. There would have to be at least a suspicion of new damning material. But maybe it was just Comey following his reporting requirements and there is nothing there. And in 2016, it appears that anything is possible, it’s the Year of the Jackpot, apparently. (Heinlein Reference)