Likely most of them are internal leaks rather than "hackers". Internal leaks and also angry agents that want nothing to do with HRC and willing to expose her. Example:
http://www.breitbart.com/jerusalem/2...eleted-emails/
HRC and this current administration likely know this, but as one psychopath said:
https://www.youtube.com/watch?v=Pb-YuhFWCr4
and that they do...