I vividly remember the day FBI director James Comey decided to publicly re-open a probe into Hillary Clinton's emails.

It was October 28th 2016, and I was in Ohio covering the latter stages of a volatile Presidential campaign.

With the election just 11 days away, the polls were wildly variable, some showing only a narrow Clinton lead over Donald Trump, others had them tied.

And with the news, America went into a spin.

The emails had already been investigated.

The State Department had written a report, and Mr Comey himself had announced in July that Ms Clinton had been "extremely careless" but that no charges would be filed over the potential compromise of classified material.

The renewed probe, unbelievably, was opened after investigators looking into sexting by former Congressman Anthony Weiner to a minor, found emails from his estranged wife on his computer that were linked to Ms Clinton.

Then-FBI director James Comey re-opened the email probe against Mrs Clinton in the final days of the 2016 campaign. ( Reuters: Jonathan Ernst )

Huma Abedin was the Clinton campaign's vice-chair.

Ahh, 2016. What a time!

Mr Trump, battling the pussy-grabbing scandal, redoubled his attacks.

He had already made the emails a key campaign issue, bringing it up over and over, and leading chants of "lock her up" at his rallies.

Two days before the election, Mr Comey announced the FBI had not changed the conclusion it reached in July.

Nothing to see here folks!

But there's a school of thought that the emails may have turned the election.

And perhaps Mr Trump agrees. He's been fixated on emails ever since.

But why are we talking about the emails again?

In August — nearly three years after the election — the State Department revived an investigation into the emails.

Why?

The department has denied any political motivation, and Ms Clinton is no longer a candidate nor does she hold any office, but plenty of people did read the (again) re-opened investigation as politically motivated.

In a nine-page conclusion delivered to Congress this week, the State Department announced that Ms Clinton's "use of a private email system to conduct official business added an increased degree of risk" that information would be compromised.

However, "there was no persuasive evidence of systemic, deliberate mishandling of classified information."

TL;DR: The emails have been investigated three times now and they've still found … nothing.

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Yet Mr Trump still hasn't given up on using emails as a weapon, but this time they may come back to bite him.

Yep, the emails relate to impeachment

Allow me to explain.

Remember the July phone call between Mr Trump and Ukrainian President Volodymyr Zelensky? It's the one that triggered the impeachment inquiry (in case you've been living under a rock).

Much of the focus has been on whether Mr Trump committed an impeachable offence by withholding military aid in return for an investigation into the son of Democratic presidential candidate Joe Biden.

But something else happened on that call.

US President Donald Trump is facing impeachment proceedings after a phone call with Ukraine's leader Volodymyr Zelensky. ( Reuters: Carlos Barria )

"I would like you to do us a favour though because our country has been through a lot and Ukraine knows a lot about it," Mr Trump says.

"I would like you to find out what happened with this whole situation with Ukraine, they say Crowdstrike … the server, they say Ukraine has it."

Might I remind you that another set of emails was making front-page news in 2016.

Those email exchanges, between high-level Democratic officials, were hacked from the Democratic National Committee server apparently by Russian intelligence.

Crowdstrike is the DC-based cybersecurity company that found Russia responsible for those hacks.

The President is alluding to a conspiracy theory, claiming there's a "secret server" containing evidence that the DNC hack was a Ukraine-backed inside job by the Democrats to blame Russia for 2016 election interference, and, you guessed it, collusion with the Trump campaign.

At a press conference after the call transcript was released, Mr Trump also seemed to endorse the idea that the two email stories might be linked when asked whether Ms Clinton's deleted emails might also be in Ukraine.

"I think they could be," he said.

"You mean the 33,000 that she deleted? Oh yeah they could be. Boy that was a nice question. I like that question."

Space to play or pause, M to mute, left and right arrows to seek, up and down arrows for volume. Watch Duration: 1 minute 12 seconds 1 m 12 s Donald Trump says Clinton emails "could be in Ukraine"

"How she got away with that one … it's just one of many. And it's corrupt government … because when you see what happened with Hillary Clinton. When you see what happened with Comey and McCabe, and we have a lot of things going on here. Hopefully it's going to be found out very soon."

Getting back to the State Department investigation…

A department under Mr Trump's administration re-opened an investigation that the FBI had long ago closed and found nothing.

In an alternative universe this may go under the radar, but in the current context, Democrats could read this as another potential use of executive power for political purposes. Or at least push that angle for their own partisan reasons.

The President's hardly helping himself on that front though.

According to data analytics company Factba.se, he has mentioned or referred to Ms Clinton an average of 2.56 times per day, or once every nine hours and 20 minutes.

He tweeted about the emails on the morning he launched his re-election campaign and still mentions "Crooked Hillary" in his stump speech.

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Trump is falling back on a strategy that worked to his advantage in 2016

For an analysis of 2016 election coverage, a pair of researchers counted sentences that appeared in mainstream media sources, classifying each as describing a scandal or a policy.



"They found roughly four times as many Clinton-related sentences that described scandals as opposed to policies, whereas Trump-related sentences were one-and-a-half times as likely to be about policy as scandal," summarised the Columbia Journalism Review.

"The various Clinton-related email scandals — her use of a private email server while secretary of state, as well as the DNC and John Podesta hacks — accounted for more sentences than all of Trump's scandals combined."

Hillary Clinton's private email server became a major issue during the 2016 election campaign. ( Reuters: Carlos Barria )

A separate study mentioned by CJR bolstered the concept:

Over the course of those six days in late October The New York Times "ran as many cover stories about Hillary Clinton's emails as they did about all policy issues combined in the 69 days leading up to the election."

Anyone reading the news could've thought the email scandal was far worse than any of Mr Trump's scandals (of which there were many), let alone policy.

Some have gone as far as to say it tipped the election.

Therefore, this new State Department report has led to some soul-searching.

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Oh, and by the way, The New York Times' coverage of the exonerating State Department report ran on page A16.

Yet Hillary still dominated the news this week

Hillary Clinton accused Democratic presidential contender Tulsi Gabbard of being a Russian asset. ( Reuters: Mike Segar/Jacob Hamilton )

Ms Clinton grabbed headlines and attracted criticism for accusing Democratic presidential candidate Tulsi Gabbard of being a "Russian asset".

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Yep, Russia. Again.

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Then, reporting emerged that some Democratic leaders, concerned that the current 2020 field doesn't have a stand-out who can beat Mr Trump, surfaced Ms Clinton's name as a potential candidate.

Yup.

That's right folks. It would seem incredible that the Democrats would actually go through with that idea, but Ms Clinton reportedly said she would consider a second run if asked.

So there's still some chance that 2020 could end up being … 2016 all over again.

If so, "but her emails" could end up being a liability for Donald Trump, rather than a weapon.