How about as a sitting United States Senator. No one seems to be talking about this but she had to have access to Secret or Top Secret materials in that position as well. If she's been keeping all correspondence privately then wouldn't that correspondence be equally vulnerable?
Hillary is probably the one that leaked the classified info about the terrorist attack that was planned for NYC in 2005.
Mayor Bloomberg got the leaked info and popped his mouth off about the planned attack even though Bush had asked him not to.