Colin Powell, in a much more sensitive position than Ivanka’s, thought it was okay.
Pay attention. We're not talking about Colin Powell. We're not talking about Hillary Clinton. We're talking about Ivanka Trump and the claim that she was too stupid to know not to use private email for government business. I guess you Trump supporters believe that she actually is too stupid to know not to use private email. I sure don't. Who's the Trump supporter now?
Besides that, even this American Thinker article admits what she did was wrong.
As for why Ivanka Trump was negligent, I have only guesses. Busy, arrogant, and careless are the first three that come to mind. Since there was no harm, and since corrective actions were taken, it is hard to get too excited.