It's been 18 hours (or so) since Hillary Clinton addressed questions about her decision to exclusively use a private e-mail address (and mail server) during her four years as secretary of state. And there's one thing, actually one number, that I just keep getting stuck on: 31,380.

That's the number of e-mails that Clinton and her lawyers deemed "private, personal records" and, therefore, neither turned over to the State Department nor preserved in any way, shape or form. What that means: Roughly half of all e-mails -- 62,320 -- that Clinton sent and received during her time as the nation's top diplomat are gone forever. And that the only way anyone can verify that they were, as Clinton insisted on Tuesday, "private" and "personal" is to take her word for it.

That fact becomes even more politically troublesome for Clinton when you consider how, according to a document her office released in the wake of her news conference, the sorting of work-related and personal e-mail was conducted. Here are the four criteria her office used:

1. Any e-mail sent to or received from an address including ".gov" was included.

2. The e-mail set was searched for the first and last name of 100 State Department employees and government officials. Any matches were reviewed.

3. All of the other e-mails were reviewed to evaluate the sender and recipient, in case of typos.

4. All of the e-mails were searched for specific terms, including "Libya" and "Benghazi."

Okay. What those criteria never make clear is whether anyone actually read every one of Clinton's 62,000-plus e-mails to determine whether there might be something in each one that could be seen as not purely personal. It's possible that the fact that the e-mails were "reviewed to evaluate the sender and recipient" could mean that someone read each one, but that language is decidedly dense (whether purposefully or not).

It all comes back to this simple fact: People being paid by Clinton reviewed -- whether individually or through a series of filtered searches -- all of her e-mails and made a decision that more than 30,000 of them were purely personal.

Do I think the vast majority of the e-mails included in that 30,000 were, as Clinton said Tuesday, "about planning Chelsea's wedding or my mother's funeral arrangements, condolence notes to friends, as well as yoga routines, family vacations, the other things you typically find in inboxes"?  Absolutely. But, is it also possible that what someone being paid by and, presumably loyal to, Clinton deemed as purely personal in terms of e-mail content might be different from how an independent arbiter of those e-mails might see them? Absolutely yes.

The problem for Clinton (or at least the problem I see) is that we won't ever be able to check whether the judgment used by her lawyers was the right judgment. I'm not suggesting that she should have been required to publicly release every e-mail -- professional or personal -- she sent during her time at State. There's plenty of private things that she has every right to keep private. But the decision to destroy all of those e-mails means that the possibility of having an independent review of them by some trusted figure (or figures) is entirely impossible.

The "just trust me" approach is tough in any part of life but especially when it comes to a person running (or about to be running) for the nation's highest office. That goes double when at issue is primary source documentation of the most recent position Clinton held before the one she plans to seek. I don't think Clinton is lying about the nature of the e-mails that were withheld from the State department and then destroyed. But I do think that the line between personal and professional communications -- especially via e-mail -- is a very fine one. And simply saying that you drew that line yourself and expecting everyone to nod their heads and move on is decidedly far-fetched.