In this Dec. 8, 2011, file photo, then-Secretary of State Hillary Rodham Clinton hands off her mobile phone after arriving to meet with Dutch Foreign Minister Uri Rosenthal at the Ministry of Foreign Affairs in The Hague, Netherlands. (AP Photo/J. Scott Applewhite, Pool/File)

Hillary Clinton's decision to exclusively use a private e-mail address -- and set up her own server at her house to do so -- during her time as the nation's leading diplomat has dominated news coverage this week. And yet, for all the great reporting that's been done, there are lots of questions that remain to be answered -- either by journalists looking into the matter or, less likely, by Clinton herself.

I put my head together with a few other reporters on The Post's national political staff -- Roz Helderman, among others -- to brainstorm a list of questions that Clinton and her team either haven't answered entirely -- or at all. Our list is below. What did we miss?

 1. Why did Clinton set this e-mail system up?

This is the biggie. Put aside the fact that other secretaries of state -- COLIN POWELL! -- have maintained a private e-mail address, no one has exclusively used such a setup. So, why did Clinton -- particular given that she had to know that it might become an issue if/when she ran for president in 2016? (No, Clinton wasn't thinking about 2016 at the start of 2009, but by the middle of her term, it was quite clear another run for president was a real possibility.)

Did she simply want to have as much control over her e-mail correspondence as possible? If so, why? Was there any political motivation in her decision, perhaps to shield some of her communication from Republicans?  Did she consider a private e-mail server more secure from hacking than the government one? If so, who advised her that way? Those are all questions no one but Clinton can answer. But it's not clear she has any plans to do so.

2. How many total e-mails did Clinton send from her private e-mail account during her four years at State?

Clintonworld has shipped 55,000 pages of e-mails to the State Department.  That much we know. What we don't know is how many more pages of e-mails exist. Here's what we do know, from a WaPo story on Thursday:

Of the e-mails that were turned over to State, the Clinton aide said, 90 percent were correspondence between Clinton and agency employees using their regular government e-mail accounts, which end in state.gov.

The remaining 10 percent were communications between Clinton and other government officials, including some at the White House, along with an unknown number of people “not on a government server,” the aide said.

That doesn't, of course, answer the more basic question. Is 55,000 the totality of the e-mails Clinton sent? Half? A third? Obviously, if it's 95 percent, that's something very different than if it's 35 percent.

3. What did Clinton mean with her tweet?

On Wednesday night, Clinton tweeted this:

But did she mean that she wants State to release the 55,000 pages she sent to State? Or all of her e-mails? If it's the latter, the burden of releasing them rests with Clinton, not the State Department. And, to reiterate question #3, just how many e-mails she sent does State not have?

4. Who was in charge of deciding which e-mails Clinton sent to State for archiving?

This is another critically important question. What we know is that someone (or someones) in Clinton's orbit went through the e-mails to decide which ones should be shipped to State. The supposed standard for withholding e-mails was that they were "personal." But, without knowing who was in charge of this selection process and what criteria they used to decide what constituted a personal e-mail, it's impossible to truly get to the bottom of what State has or, more importantly, should have.

5. Did anyone at State or the White House raise a worry about Clinton's exclusive use of the private e-mail system?

This from Edward Isaac-Dovere's piece at Politico today:

The White House, State Department and Hillary Clinton’s personal office knew in August that House Republicans had received information showing that the former secretary of state conducted official government business through her private email account — and Clinton’s staff made the decision to keep quiet.

Sources familiar with the discussions say key people in the Obama administration and on Clinton’s staff were aware that the revelation could be explosive for the all-but-announced candidate for president. But those involved deferred to Clinton’s aides, and they decided not to respond.

The larger question is did anyone -- at the State Department or the White House -- not raise a red flag earlier about her e-mail being a problem before it became clear that said information had fallen into the hands of Republican congressional investigators? If someone did, what was Clinton's response -- or did the matter never get all the way to her? If no one raised an alarm, why not?

6. How do we know there was no classified material in those e-mails? What about "sensitive" material and, if they did include "sensitive" material, did her e-mail system meet State Department security requirements for the exchange of such information?

Here's what we know about what was in the e-mails Clinton sent, via the New York Times:

While the State Department has said there does not appear to be any classified material in Mrs. Clinton’s emails, officials said on Thursday that they needed to go through the trove again to determine whether it contained any “sensitive” information.

Sensitive information is different from classified information. It can be personal data, like Social Security numbers, or information on matters that other countries consider classified or important to their national security.

So there "does not appear" to be any classified information contained therein, but it remains to be seen if there was "sensitive" information. That sounds like the State Department is giving itself lots of wiggle room. It may turn out that there was no classified or even "sensitive" information transmitted but it's quite clear that we -- and State -- don't know that yet. And, since we don't know that, we also don't know if there was ever a conversation between Clinton and State Department officials about how and whether she could send this sort of information via a private e-mail server.