When it comes to Republican Donald Trump repeated attacks about her husband's sex life, Hillary Clinton has one message for Donald Trump: "Didn't work before, won't work again."

Trump has spent weeks attacking former President Bill Clinton on the campaign trail, calling him "one of the great abusers of the world" and comparing him to Bill Cosby, who is facing sexual assault allegations.

"If he wants to engage in personal attacks from the past, that's his prerogative," she said. "I'm going to draw the distinctions between where I stand and where he stands," especially on issues like equal pay and the minimum wage.

"He can say whatever he wants to about me. Let the voters judge that, but I am not going to let him or any of the other Republicans rip away the progress that women have made," Clinton said. "It's been too hard fought for and I'm going to stand up and make it clear there's a huge difference between us."

Even some Democrats say that part of her husband's career is fair game, moderator John Dickerson pointed out. Clinton said Republicans can try it again if they want, but it "didn't work before, won't work again."

"I can't run anybody else's campaign. They can say whatever they want, more power to them," she said. "I think it's a dead end, blind alley for them but let 'em go."

Clinton also addressed questions over the latest questions over her email practices and said she never sent classified information over private email server while serving as secretary of state, even though a newly-released email shows her instructing an aide on how to send talking points through a non-secure system.

"As the State Department said just this week that did not happen and it never would have happened because that's just not the way I treated classified information," Clinton said Sunday in an interview on CBS' "Face the Nation."

The Democratic presidential candidate has repeatedly insisted that no classified information was sent or received through her private email server. But in one email exchange between Clinton and staffer Jake Sullivan from June 17, 2011, Clinton advised Sullivan to send a set of talking points by email when he had trouble sending them through secure means.

Part of the exchange is redacted, so the context of the emails is unknown. After Sullivan that aides were having "issues" sending the emails through secure fax, Clinton responded, "If they can't, turn into nonpaper w no identifying heading and send nonsecure."

It's unclear whether the talking points themselves contained classified information. Typically, talking points are used for unclassified purposes (e.g. speaking with the media). But in some cases, the material contained in such memos may still be sensitive -- especially if the report originates from intelligence agencies.

Clinton said in the interview that this was "common practice." While she would have to wait for the secure fax to give her the "whole picture," she said, "There is a lot of information that isn't at all classified so whatever information can be appropriately transmitted unclassified often was."

"That's true for every agency in the government," she added.

Clinton also said she had "great confidence" in Sullivan, the aide she corresponded with. She described him as "the most meticulous, careful person you could possibly do business with" and said he knew exactly what was and was not appropriate.

She said the questions over the talking points is "another effort by people looking for something to throw against the wall."

"There's no 'there' there," she concluded.

The FBI is probing whether State Department officials improperly included classified material in email correspondence with Clinton.

Regarding another email exchange in which Clinton expressed surprise that someone emailed her from a non-government account - which Clinton herself did while secretary of state - she said she always emailed people on their official State Department accounts so it would become a part of the official record.

"That's how I conducted the business. I was very clear about emailing, anything having to do with business to people on their government accounts," she said.

On the subject of her presidential campaign, Clinton brushed off a new NBC News/Wall Street Journal poll released Sunday morning that shows her leading rival Sen. Bernie Sanders, I-Vermont, by just three percentage points (48 to 45) among likely Iowa caucus voters.

"These polls go up, they go down. I stay pretty focused as I think we all should on what we have to do to build on the progress of the Obama administration but go even further," she said.