The emails also paint a picture that confirms what has long been assumed, that of a DNC more or less isolated from key elements of the party - including the White House - and left to the devices of its long-standing chair, Congresswoman Debbie Wasserman Schultz, of Florida.
It was clear last northern autumn that for whatever reason, whether outright favouritism toward Clinton or something else, the Democratic debate schedule - limited in number and out of sync with many of the early primaries and caucuses - was initially more helpful to Clinton than her challengers.
Wasserman Schultz denied it - those Saturday night debates, she said correctly, came at the demands of the major broadcast networks - but Clinton's rivals weren't buying.
After seeing what was being said about Sanders in some of the emails, the senator from Vermont and his advisers have concluded that Wasserman Schultz and others were quietly cheering for Clinton. Sanders now has every right to feel aggrieved.
But this is more than an issue of whether Sanders got fair treatment. The problems at the DNC date back years. Obama came to the presidency without deep ties to the institutions of the party. He owed few people much and liked it that way.
During the first two years of his presidency, the DNC was used to develop and test some of the infrastructure - data collection, analytics and modeling techniques - that allowed them to jump-start the work of his 2012 reelection committee. Though it took most of 2011 and much of 2012 to perfect those tools (though they weren't always perfected), the re-election team had a running start because of what was funded through the DNC.
Other than that, the Obama political operation has been largely separate and freestanding, through various committees with the initials OFA - Obama for America, Organising for America, etc. The DNC competed for money with those Obama-linked organisations. Also, it wasn't until the northern summer of 2015 that the Obama committees' information was fully shared with the national committee.
In 2010, at a meeting of Democratic governors, one governor asked an Administration official, "Will the OFA please join the Democratic Party."
Obama has helped raise funds for the DNC, but overall its fundraising has trailed that of the Republican National Committee. According to data on the campaign finance watchdog Open Secrets, the DNC had raised US$128 million this cycle compared with US$181 million for the RNC. The party that holds the White House should do better than that.
Given her role, Wasserman Schultz has been one of the most visible faces of the party, a frequent guest on cable television who has delivered the party's talking points about the opposition with robotic discipline. But she has been a controversial chair, with Democrats privately questioning her effectiveness as a spokeswoman and a party builder. The email leaks have turned that into a public conversation.
Today, Sanders called for her to resign. This is not the first such call for removal. Wasserman Schultz is no favourite of Democratic congressional leaders, who earlier this year floated the possibility that she could be moved aside before the election. It hasn't happened, in part because it could easily be done unless she was willing to go.
Today Wasserman Schultz announced abruptly that she would step down at week's end.
Clinton's team has long known that Wasserman Schultz is an unpopular chair. But the feeling inside the Brooklyn campaign headquarters has always been that her removal wasn't worth the time, effort or public brouhaha.
As president, she would probably restructure the committee and bring in her own chair to run it
The Clinton campaign always had bigger issues to deal with, like winning the nomination against a stronger-than-expected challenge from Sanders and now dealing with Donald Trump, an opponent who plays by new rules. Worrying about the chair of the party through all this seemed like a small-bore problem, which it was. They were always content to let things go through the duration of the campaign.
The Washington Post reported in June that Russian Government hackers had penetrated the DNC's computers and stolen opposition research about Trump. Making the rounds of the talk shows, Robby Mook, Clinton's campaign manager, said experts had informed the campaign that the email leak was the work of Russians trying to help Trump.
The timing of the leak certainly seems more than coincidental, and that leaves open the possibility that more material will come in the future.
The release has left Wasserman Schultz embattled at the start of a convention that she and the DNC have been planning for many months. She was highly visible on Sunday at the rally where Clinton unveiled her vice-presidential running-mate, Senator Timothy Kaine of Virginia.
But she could be a diminished figure here this week, in contrast to Republican National Committee Chair Reince Priebus last week in Cleveland. Priebus, who has had the difficult job of operating as a liaison with Trump, was given a prominent speaking slot last Friday in Cleveland.
Wasserman Schultz's exact role and visibility here this week are relatively small issues, though cable commentators will be able to chew it on until the convention opens tomorrow. The larger question is how this affects efforts to project unity and what happens to the leadership of the DNC now and later.
Clinton cares more about party-building and party institutions than Obama. She made it part of her campaign appeal as she worked to gain support of state party officials and other super delegates during the primaries. As president, she would probably restructure the committee and bring in her own chair to run it.
There will be pressure now to accelerate that timetable, but there's no good short-term solution. For the Democrats, it's ironic that a long-standing problem has become visible at exactly the wrong moment.
