Right now:
Unfavorable: 48.4
Favorable: 41.5
There's no denying that a -7 favorability is is an unfavorable (get it?) place to be in. However, look at
Obama's approvals.
Disapprove: 50%
Approve: 45.6%
Obama's not in too good of a position either, a -4.5 approval rating isn't a nice position either. Clinton's unfavorable score is actually lower than his disapproval rating. Its just that her favorable score is in much lower than his approval rating.
She's not in a hole she can't dig herself out of.
If the email situation blows over and the party unifies behind her once she's nominated, its likely that she's return to break-even. Of course, if she's indicted, its game over for her.