When the University of Missouri at Kansas City asked former Secretary of State Hillary Clinton to speak at the opening of the school's new women's hall of fame in 2014, they were surprised to learn how much her appearance would cost.

"Yikes!" read one university official's response to the quoted fee of $275,000, according to emails obtained by the Washington Post.

Instead of forking over the large sum, the university instead paid $65,000 for Chelsea Clinton, the former first daughter, to speak at the event.

The Clintons' speaking fees -- from which they've earned huge sums of money -- have come under scrutiny since Hillary Clinton's 2016 presidential campaign started to ramp up. From January 2014 through early May 2015, former President Bill Clinton and Hillary Clinton together earned more than $25 million from about a total of 100 paid speeches, a Clinton campaign official told CBS News. Hillary Clinton's speaking fees ranged from about $100,000 to over $300,000.

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However, Mrs. Clinton has said that every dollar she's earned speaking at universities since stepping down as secretary of state has gone into the philanthropic work of the Clinton Foundation. Earlier this year, the foundation listed online the funds it has raised through the Clintons' speaking fees.

Chelsea Clinton's spokesman told the Post that the fee collected from the University of Missouri at Kansas City also went to the foundation.