“as has been pointed out by the FBI that stated that there were emails marked classified at the time”
Actually only three were — and none of the three were marked properly. They only had a (c) before the classified line; red stamps “CONFIDENTIAL” at the top and bottom were also required. And at least two of the three had already been declassified at the time she sent them; the State Department indicated that it is possible that the third one was as well but they have not been able to confirm it.
Meanwhile, while nobody knew about Clinton’s server, the official secure servers at the State Department lost two hundred fifty two thousand, two hundred eighty two messages to Wikileaks. Nothing from Clinton’s server appeared on Wikileaks. And given that the link between Wikileaks and Russians has now been proven, it is likely that her emails would have ended up there had it been successfully hacked.