Here is an example of the double standard:
Clinton's use of emails in the state department was investigated by the FBI and discussed ad nausea. At the end of the day, no criminal charges were filed.
Trumps casinos were also investigated, by the Financial Crimes Enforcement Network, and found GUILTY for "significant and long-standing anti-money laundering violations" and fined 10M.
How much did we hear about that during the campaign? which of those two things are potentially worse given all we know about Trump is that
(1) he has significant financial ties to Russia and associate with known shady Russian people
(2) one of his companies was found guilty of anti-money laundering violations
(3) Russia interfered on his behalf during the election
(4) he has not released 1 page of tax documents.
(5) his first acts as president will be to go to Russia, he has appointed some of the most pro-Russia people to highest positions in his government and he is already talking about lifting sanctions despite the recent hacking.
This is looking shady as hell but for some reason the narrative that the emails are of the utmost importance keeps getting pushed even by the left.