One of the animating chapters in the Trump-Russian collusion saga was the claim that Russia infiltrated the Democratic National Committee’s email server in the spring of 2016. That hack, according to collusion truthers, and the subsequent release of damaging emails exchanged between top Democratic Party officials was central to Vladimir Putin’s scheme to sway the presidential election in favor of Donald Trump. But the evidence to support this widely accepted claim is sketchy at best and appears to be under appropriate scrutiny by prosecutors now examining the origins of the FBI’s pre-election investigation into the Trump campaign for “colluding” with...