Washington (CNN) The State Department released the very last of Hillary Clinton's work-related emails Monday, capping off a nearly year-long process that began when The New York Times revealed that Clinton had been exclusively using a private server to conduct official business as secretary of state.

For the State Department, the Clinton campaign and journalists covering the story, the releases have been at various times tedious, contentious, frustrating, revealing and opaque.

Here's what we've learned so far, and what remains unanswered.

All the emails are out, but the controversy isn't over

Monday's final release marks the end of a major effort by the State Department's Freedom of Information Act office, which had to review more than 52,000 pages of the former secretary of state's emails in the past year before releasing them to the public.

Clinton called for the emails to be released when news of her unusual communications set-up was first revealed. The State Department was then ordered to provide them to the public on a rolling basis by a federal judge in a FOIA lawsuit.

But it would be premature for those staffers to celebrate, since the department is still in the midst of processing dozens of related requests.

The State Department is furthermore being sued for the emails of top aides, and for the tens of thousands of emails Clinton deemed personal and didn't turn over for review.

At a hearing last week in one such lawsuit, U.S. District Judge Emmet Sullivan said he's considering asking the State Department to subpoena Clinton, and aide Huma Abedin, in an effort to learn more about those emails.

And Clinton's emails continue to get scrutiny beyond the State Department. On Monday, State Department Spokesman John Kirby told reporters one email is being withheld from the public in full at the request of law enforcement.

Kirby would not comment on the content of the email, but he emphasized it is not classified.

Clinton's server is also the subject of an FBI investigation, which has allowed her Republican opponents on the presidential campaign trail to raise the specter of possible indictment.

In an interview Monday with Fox News, Attorney General Loretta Lynch said the investigation is "being handled like any other review that we do into how any agency has handled classified information," but she had no updates on the time frame for its completion.

"What's most important is to follow the facts, follow the law, and come to an independent conclusion as to what may or may not have happened," she said.

Classification is messy

Much of the conversation surrounding Clinton's use of a private server for State Department business has revolved around the question of whether she took adequate measures to safeguard sensitive information.

Clinton and her aides insist none of the emails she sent or received were marked as classified at the time they were sent, but more than 2,101 have been retroactively classified during the State Department-ledpre-release review process.

This includes 22 emails upgraded to Top Secret -- the highest level -- and withheld by the State Department in full.

Those emails in particular are the subject of intense scrutiny, sometimes leaving the State Department and intelligence community at odds.

Last month, a leaked letter from intelligence community Inspector General I. Charles McCullough III revealed the existence of "several dozen" cases of classified information originating from intelligence agencies, some of which, they said, should have been considered classified during Clinton's tenure.

Those documents included information on so-called "Special Access Programs," a highly sensitive subset of information off limits even to most Top Secret clearance holders.

Clinton's campaign has waded into the fray, suggesting the upgrades and intelligence agency disparities are the result of "over-classification run amok." Clinton campaign spokesman Brian Fallon has also blamed political operatives in the inspector general's office and on Capitol Hill for leaking information about the normally secretive review process.

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Little is known about the content of the most sensitive emails beyond what's been outlined in McCullough's letter, but Democratic California Sen. Dianne Feinstein, a member of the Senate intelligence committee who has seen the now-Top Secret communications, recently said in a statement that "none of those email chains originated with Secretary Clinton."

"It has never made sense to me that Secretary Clinton can be held responsible for email exchanges that originated with someone else," she added.

As a sign that the inter-agency debate continued until the very last days of the review, State Department Spokesman John Kirby told reporters Monday that one email flagged by the intelligence community as potentially containing Top Secret information was deemed not to have and will be released Monday with limited redactions and upgrades.

That email, released in in Monday's batch, involved information about a conference call on North Korea, convened after the country conducted a missile test in July 2009. The now-classified information was sent by a career diplomat and forwarded to Clinton by Abedin.

The ongoing debate over classification has led the State Department to announce a separate review, led by the Bureaus of Diplomatic Security and Intelligence and Research, into whether any of the information retroactively upgraded should have been marked as classified when sent.

Clinton never lost her interest in politics

Cabinet posts are theoretically outside of the political sphere, but Clinton was kept keenly aware of the political climate throughout her tenure.

Aides often forwarded Clinton information on her favorability ratings, even as she told the public she was undecided on making another run for the White House.

In March 2009. Mills forwarded her a CNN poll showing "Clinton has high job approval."

Reines sent her a similar poll two years later, adding, "This is why we cooperate with so many profiles - and just wait until 19 million Americans to read PEOPLE next week."

Blumenthal frequently offered his thoughts on politics, writing enthusiastically in 2010, "can you call me now? eureka idea for midterms!! want to run by you, think it can work."

Friends and staffers heaped on flattery

Clinton's core staff at the State Department was both loyal and adoring, as evidenced by the dozens of praise emails she received on a regular basis.

Aides frequently forwarded positive articles about Clinton, including a Drudge Report piece titled "Clinton Popularity Prompts Buyer's Remorse."

When a photo of Clinton on her Blackberry turned into a viral Internet meme, Cheryl Mills wrote simply, "You look cute."

And the praise didn't just come from her staff.

On January 23, 2013, after Clinton testified before the Senate Foreign Relations Committee on the Benghazi consulate attack, top White House economic adviser Gene Sperling wrote to Mills that Clinton "was a great combo of patient, emotional and fighting-back tough. Made me proud." That email was forwarded to Clinton.

Another Obama administration official, Liz Sherwood-Randall, wrote to Sullivan: "If you get a chance — please tell HRC that she was a ROCK STAR yesterday. Everything about her 'performance' was what makes her unique, beloved, and destined for even more greatness."

"She sets a standard that lesser mortals can only dream of emulating," Sherwood-Randall added.

Top aides join Clinton in the crosshairs

Among the emails retroactively classified at the lower tiers of Confidential and Secret are communications between top State Department officials, foreign dignitaries and advisers outside of the U.S. government, who weighed in on a number of policy discussions.

Many of those emails were not sent to Clinton directly but rather were forwarded to her by key aides, including Chief of Staff Cheryl Mills, Deputy Chief of Staff Huma Abedin and Jake Sullivan, who served as both director of policy planning and deputy chief of staff.

Abedin and Sullivan currently hold top positions on Clinton's presidential campaign.

Clinton's core team at the State Department was, in some ways, insular.

Senior officials who didn't know her email address often emailed Abedin, Mills or Sullivan when they needed to convey messages to the secretary, showing how access to her was carefully managed.

In a July 2012 email forwarded to Clinton, staffer Philippe Reines humorously alluded to the closed nature of the former secretary's inner circle by creating a flow chart to determine who would ride with her on the road.

The chart asked a series of yes or no questions starting with, "Huma there?," and ending with scenarios in which Reines himself might be allowed to join in the vehicle.

Clinton sought guidance from many sources

Aside from her inner circle, Clinton also received emails from some of her department's top officials, including now-classified emails from then-Deputy Secretary William Burns and former Under Secretary of State for Political Affairs Wendy Sherman.

She also heard regularly from Tony Blair, the former British prime minister who served as a Middle East peace envoy for the United Nations at the time, and on occasion from Ashraf Ghani, a prominent Afghani politician who has since become president of that country.

Clinton also received emails from her eventual successor at the State Department, John Kerry, who chaired the Senate Foreign Relations Committee during her years in office and himself sometimes emailed from a personal email account.

Photos: Hillary Clinton's life in the spotlight Photos: Hillary Clinton's life in the spotlight Hillary Clinton accepts the Democratic Party's nomination for president at the Democratic National Convention in Philadelphia on July 28, 2016. The former first lady, U.S. senator and secretary of state was the first woman to lead the presidential ticket of a major political party. Hide Caption 1 of 43 Photos: Hillary Clinton's life in the spotlight Before marrying Bill Clinton, she was Hillary Rodham. Here she attends Wellesley College in Massachusetts. Her commencement speech at Wellesley's graduation ceremony in 1969 attracted national attention. After graduating, she attended Yale Law School. Hide Caption 2 of 43 Photos: Hillary Clinton's life in the spotlight Rodham was a lawyer on the House Judiciary Committee, whose work led to impeachment charges against President Richard Nixon in 1974. Hide Caption 3 of 43 Photos: Hillary Clinton's life in the spotlight In 1975, Rodham married Bill Clinton, whom she met at Yale Law School. He became the governor of Arkansas in 1978. In 1980, the couple had a daughter, Chelsea. Hide Caption 4 of 43 Photos: Hillary Clinton's life in the spotlight Arkansas' first lady, now using the name Hillary Rodham Clinton, wears her inaugural ball gown in 1985. Hide Caption 5 of 43 Photos: Hillary Clinton's life in the spotlight The Clintons celebrate Bill's inauguration in Little Rock, Arkansas, in 1991. He was governor from 1983 to 1992, when he was elected President. Hide Caption 6 of 43 Photos: Hillary Clinton's life in the spotlight Bill Clinton comforts his wife on the set of "60 Minutes" after a stage light broke loose from the ceiling and knocked her down in January 1992. Hide Caption 7 of 43 Photos: Hillary Clinton's life in the spotlight In June 1992, Clinton uses a sewing machine designed to eliminate back and wrist strain. She had just given a speech at a convention of the International Ladies' Garment Workers Union. Hide Caption 8 of 43 Photos: Hillary Clinton's life in the spotlight During the 1992 presidential campaign, Clinton jokes with her husband's running mate, Al Gore, and Gore's wife, Tipper, aboard a campaign bus. Hide Caption 9 of 43 Photos: Hillary Clinton's life in the spotlight Clinton accompanies her husband as he takes the oath of office in January 1993. Hide Caption 10 of 43 Photos: Hillary Clinton's life in the spotlight The Clintons share a laugh on Capitol Hill in 1993. Hide Caption 11 of 43 Photos: Hillary Clinton's life in the spotlight Clinton unveils the renovated Blue Room of the White House in 1995. Hide Caption 12 of 43 Photos: Hillary Clinton's life in the spotlight Clinton waves to the media in January 1996 as she arrives for an appearance before a grand jury in Washington. The first lady was subpoenaed to testify as a witness in the investigation of the Whitewater land deal in Arkansas. The Clintons' business investment was investigated, but ultimately they were cleared of any wrongdoing. Hide Caption 13 of 43 Photos: Hillary Clinton's life in the spotlight The Clintons hug as Bill is sworn in for a second term as President. Hide Caption 14 of 43 Photos: Hillary Clinton's life in the spotlight The first lady holds up a Grammy Award, which she won for her audiobook "It Takes a Village" in 1997. Hide Caption 15 of 43 Photos: Hillary Clinton's life in the spotlight The Clintons dance on a beach in the U.S. Virgin Islands in January 1998. Later that month, Bill Clinton was accused of having a sexual relationship with former White House intern Monica Lewinsky. Hide Caption 16 of 43 Photos: Hillary Clinton's life in the spotlight Clinton looks on as her husband discusses the Monica Lewinsky scandal in the Roosevelt Room of the White House on January 26, 1998. Clinton declared, "I did not have sexual relations with that woman." In August of that year, Clinton testified before a grand jury and admitted to having "inappropriate intimate contact" with Lewinsky, but he said it did not constitute sexual relations because they had not had intercourse. He was impeached in December on charges of perjury and obstruction of justice. Hide Caption 17 of 43 Photos: Hillary Clinton's life in the spotlight The first family walks with their dog, Buddy, as they leave the White House for a vacation in August 1998. Hide Caption 18 of 43 Photos: Hillary Clinton's life in the spotlight President Clinton makes a statement at the White House in December 1998, thanking members of Congress who voted against his impeachment. The Senate trial ended with an acquittal in February 1999. Hide Caption 19 of 43 Photos: Hillary Clinton's life in the spotlight Clinton announces in February 2000 that she will seek the U.S. Senate seat in New York. She was elected later that year. Hide Caption 20 of 43 Photos: Hillary Clinton's life in the spotlight Clinton makes her first appearance on the Senate Environment and Natural Resources Committee. Hide Caption 21 of 43 Photos: Hillary Clinton's life in the spotlight Sen. Clinton comforts Maren Sarkarat, a woman who lost her husband in the September 11 terrorist attacks, during a ground-zero memorial in October 2001. Hide Caption 22 of 43 Photos: Hillary Clinton's life in the spotlight Clinton holds up her book "Living History" before a signing in Auburn Hills, Michigan, in 2003. Hide Caption 23 of 43 Photos: Hillary Clinton's life in the spotlight Clinton and another presidential hopeful, U.S. Sen. Barack Obama, applaud at the start of a Democratic debate in 2007. Hide Caption 24 of 43 Photos: Hillary Clinton's life in the spotlight Obama and Clinton talk on the plane on their way to a rally in Unity, New Hampshire, in June 2008. She had recently ended her presidential campaign and endorsed Obama. Hide Caption 25 of 43 Photos: Hillary Clinton's life in the spotlight Obama is flanked by Clinton and Vice President-elect Joe Biden at a news conference in Chicago in December 2008. He had designated Clinton to be his secretary of state. Hide Caption 26 of 43 Photos: Hillary Clinton's life in the spotlight Clinton, as secretary of state, greets Russian Prime Minister Vladimir Putin during a meeting just outside Moscow in March 2010. Hide Caption 27 of 43 Photos: Hillary Clinton's life in the spotlight The Clintons pose on the day of Chelsea's wedding to Marc Mezvinsky in July 2010. Hide Caption 28 of 43 Photos: Hillary Clinton's life in the spotlight In this photo provided by the White House, Obama, Clinton, Biden and other members of the national security team receive an update on the mission against Osama bin Laden in May 2011. Hide Caption 29 of 43 Photos: Hillary Clinton's life in the spotlight Clinton checks her Blackberry inside a military plane after leaving Malta in October 2011. In 2015, The New York Times reported that Clinton exclusively used a personal email account during her time as secretary of state. The account, fed through its own server, raises security and preservation concerns. Clinton later said she used a private domain out of "convenience," but admits in retrospect "it would have been better" to use multiple emails. Hide Caption 30 of 43 Photos: Hillary Clinton's life in the spotlight Clinton arrives for a group photo before a forum with the Gulf Cooperation Council in March 2012. The forum was held in Riyadh, Saudi Arabia. Hide Caption 31 of 43 Photos: Hillary Clinton's life in the spotlight Obama and Clinton bow during the transfer-of-remains ceremony marking the return of four Americans, including U.S. Ambassador Christopher Stevens, who were killed in Benghazi, Libya, in September 2012. Hide Caption 32 of 43 Photos: Hillary Clinton's life in the spotlight Clinton ducks after a woman threw a shoe at her while she was delivering remarks at a recycling trade conference in Las Vegas in 2014. Hide Caption 33 of 43 Photos: Hillary Clinton's life in the spotlight Clinton, now running for President again, performs with Jimmy Fallon during a "Tonight Show" skit in September 2015. Hide Caption 34 of 43 Photos: Hillary Clinton's life in the spotlight Clinton testifies about the Benghazi attack during a House committee meeting in October 2015. "I would imagine I have thought more about what happened than all of you put together," she said during the 11-hour hearing. "I have lost more sleep than all of you put together. I have been wracking my brain about what more could have been done or should have been done." Months earlier, Clinton had acknowledged a "systemic breakdown" as cited by an Accountability Review Board, and she said that her department was taking additional steps to increase security at U.S. diplomatic facilities. Hide Caption 35 of 43 Photos: Hillary Clinton's life in the spotlight U.S. Sen. Bernie Sanders shares a lighthearted moment with Clinton during a Democratic presidential debate in October 2015. It came after Sanders gave his take on the Clinton email scandal. "The American people are sick and tired of hearing about the damn emails," Sanders said. "Enough of the emails. Let's talk about the real issues facing the United States of America." Hide Caption 36 of 43 Photos: Hillary Clinton's life in the spotlight Clinton is reflected in a teleprompter during a campaign rally in Alexandria, Virginia, in October 2015. Hide Caption 37 of 43 Photos: Hillary Clinton's life in the spotlight Clinton walks on her stage with her family after winning the New York primary in April. Hide Caption 38 of 43 Photos: Hillary Clinton's life in the spotlight After Clinton became the Democratic Party's presumptive nominee, this photo was posted to her official Twitter account. "To every little girl who dreams big: Yes, you can be anything you want -- even president," Clinton said. "Tonight is for you." Hide Caption 39 of 43 Photos: Hillary Clinton's life in the spotlight Obama hugs Clinton after he gave a speech at the Democratic National Convention in Philadelphia. The president said Clinton was ready to be commander in chief. "For four years, I had a front-row seat to her intelligence, her judgment and her discipline," he said, referring to her stint as his secretary of state. Hide Caption 40 of 43 Photos: Hillary Clinton's life in the spotlight Clinton arrives at a 9/11 commemoration ceremony in New York on September 11. Clinton, who was diagnosed with pneumonia two days before, left early after feeling ill. A video appeared to show her stumble as Secret Service agents helped her into a van. Hide Caption 41 of 43 Photos: Hillary Clinton's life in the spotlight Clinton addresses a campaign rally in Cleveland on November 6, two days before Election Day. She went on to lose Ohio -- and the election -- to her Republican opponent, Donald Trump. Hide Caption 42 of 43 Photos: Hillary Clinton's life in the spotlight After conceding the presidency to Trump in a phone call earlier, Clinton addresses supporters and campaign workers in New York on Wednesday, November 9. Her defeat marked a stunning end to a campaign that appeared poised to make her the first woman elected US president. Hide Caption 43 of 43

Not immune from the controversy, several emails sent by Kerry have now been upgraded to classified, including a few in Monday's batch.

Perhaps the most controversial member of her kitchen cabinet was Sidney Blumenthal, a friend and confidant who sent her hundreds of emails on both policy and politics, even though he was blocked by the Obama administration from joining her official team at the State Department.

Critics have wondered why Blumenthal had such direct access to, and perhaps influence over, Clinton, when many officials in her own department didn't have her personal email address.

Clinton has dismissed the extent of Blumenthal's influence, calling the emails "unsolicited," even as she thanked him repeatedly at the time for offering his perspective.

"I'm going to keep talking to my old friends, whoever they are," Clinton said during a May press conference in Iowa. "He's been a friend of mine for a long time. He sent me unsolicited emails, which I passed on in some instances, and that's just part of the give-and-take."

Unsurprisingly, Clinton emailed family members as well. And it was an email to daughter Chelsea Clinton on the night of the attack on the U.S. consulate in Benghazi that brought Clinton pointed questions when she testified before the House Select Committee on Benghazi in November, as some lawmakers wondered why she attributed the attack to "an Al Queda-like group" in the email while publicly suggesting protesters played a role.

Clinton's email set-up was discussed by staff

Despite her unusual decision to set up a private email server at her home, Clinton's communications often display a lack of savvy when it comes to technology.

In a June 2010 email to Reines, Clinton is excited to learn that her new iPad (called the "hPad" by her loyal staffers) has arrived, and asks, "do you think you can teach me to use it on the flight to Kyev next week."

And even as she elected not to use a state.gov account, Clinton expressed surprise when other staffers did the same.

At one point in 2011, Sullivan passed along insights from a State Department employee using a personal account, prompting Clinton to ask, "Who does he work for now?"

When Sullivan said the man worked for the State Department, Clinton responded, "I was surprised that he used personal email account if he is at State."

Other emails reflect Clinton's frustration with the State Departments communications systems, and the limits presented by the very systems meant to protect classified information.

In one such email, Sullivan tells Clinton a statement by Blair was put on the classified system "for reasons that elude me," prompting Clinton to reply: "It's a public statement! Just email it."

"Trust me, I share your exasperation," Sullivan replied. "But until ops converts it to the unclassified email system, there is no physical way for me to email it. I can't even access it."

On a separate occasion, Clinton and Sullivan exchange emails on a set of "tps" -- presumably talking points, which he's trying to send to her on a secure fax line.

"If they can't," Clinton replies, "turn into nonpaper w no identifying heading and send nonsecure."

There's no indication whether the talking point were classified, but the exchange led to criticism from Republican Iowa Sen. Chuck Grassley, a frequent Clinton critic, who called the chain "disturbing" and asked the former secretary to "come clean."

Additional emails, on which Clinton was not copied, also shed light on how her email set-up was viewed at the State Department.

A set of emails released to the website The Daily Caller last month, for instance, show that some officials suggested providing Clinton with a State Department Blackberry, which Huma Abedin resisted.

"Let's discuss the state blackberry, doesn't make a whole lot of sense," she replied.

There were also discussions about setting up a "stand-alone PC" for Clinton that would allow her to access her personal emails at the State Department.

In an email exchange later obtained by the conservative legal watchdog group Judicial Watch, Under Secretary for Management Patrick Kennedy tells Mills the computer "is a great idea."

Ultimately, State Department officials say the computer was not set up. It's unclear why the idea was ultimately nixed, but it might relate to Clinton's lack of computer knowledge, as relayed in a later email.

"I talked to Cheryl about this," Lewis Lukens, then a deputy assistant secretary of state, writes. "She says a problem is hrc does not know how to use a computer to do email -- only [Blackberry]. But, I said would not take much training to get her up to speed."