2016 Postmortem

Legal, ethical, doesn't matter.

It opened up her opponents to make plausible accusations that her private email server was a necessary requirement to facilitate business dealings for the Clinton Foundation away from the public eye. And when she claimed that 30,000 deleted emails were about yoga routines and wedding plans, even her supporters cringed. Even worse, once this seed of impropriety was placed in the heads of Joe Public, it became easier for her opponents to insinuate that the CFF was a slush fund making the Clintons rich and that's why everything had to be kept hush hush. For crying out loud, there was a New York Times best-seller making this very case!

Bad optics? That's an understatement. It paved the way for the whole "Crooked Hillary" meme that Trump was able to use quite effectively.