Interestingly, during the 2016 campaign, everywhere Trump went he led a repeated cheer of “Lock her up” because of her e-mail server (which was found to be quite secure). After taking over the White House, Trump continued to use his private, insecure cell phone to tweet. Somebody tried to see if he could hack the account and was able to get in , so he notified the White House about it. More than a week later when he found the problem was not corrected, he went public with the information, since foreign entities would be trying to do this and he felt that somebody should get it straightened out. I don’t know if it ever was straightened out but Ivanka (one of his “private” advisors) is still using private e-mail for some government business.