The emails were released Tuesday by the Southern Poverty Law Center after being leaked to the organization by a former Breitbart editor, Katie McHugh. McHugh was released in 2017 following anti-Muslim statements following a terrorist attack in London.
In the years since she was with Breitbart, McHugh has renounced her views and campaigned to unmask members of the Right.
Neither Miller nor The White House responded to a CNN request for comments on the latest emails. Rubio's office also did not respond to a CNN request for comments.
Elizabeth Moore, a Breitbart spokeswoman, told CNN, "The SPLC claims to have three to four year old e-mails many had previously reported involving one person And now you have an even better idea of why we fired them, and besides that, it's not exactly news that political officials tell stories to journalists ̵
Breitbart also published a Miller-written press release entitled "Breitbart News." what Miller suggested.
"I think Breitbart News (should be the byline)," said Miller Breitbart editor Matthew Boyle. "Then it can be introduced as something exclusively shared by the Senate Subcommittee (sic) for immigration and national interest with Breitbart, with the graphic and explanatory text underneath."
Others copied to the e-mail included Steve Bannon, who directed the right-wing extremist website at that time, session advisors Garrett Murch, McHugh, and three other Breitbart employees. In another email, Miller said, the publication should summarize a piece written by a conservative expert who criticized Rubio's presidential election. An article on this topic was published hours later on the Breitbart website.
"My editors expected me to take white nationalist material from Stephen Miller and incorporate it into news stories to boost Donald Trump's campaign," McHugh told CNN in a telephone interview.
"That's how it starts," said Miller's subject line.
In December 2015, he wrote: "The only difference between Jeb [Bush] and Rubio is that Jeb is honest and Rubio is pathological [.]." "Stephen Miller seemed to have a very specific revenge on Marco Rubio, who would always call him an extremist if it was Miller who was extremist," she said.
"Miller attempted to orchestrate the idea of this narrative that not only people of skin color or people who are Muslims are dangerous individuals, but that they pose an existential threat to the country he wanted to promote," she added
Michael Edison Hayden, an employee of the Southern Poverty Law Center, reviewed the e-mail leaked by McHugh and said that Miller's emails about Rubio were sometimes racially motivated.
"With Marco Rubio, (Miller) has done what I would call highly racially motivated attacks, for example, an e-mail in which he sends the subject" How it starts ". Mail contains an article about the diversity of the GOP nomination and states that Rubio is a Cuban American, "Hayden told CNN.
In another section of the e-mail, Miller writes to the right-wing extremist website the death of Rubio's co-funded "Gang of Eight" immigration bill.
"Without Breitbart, the bill would have become law," Miller wrote in an e-mail that included Breitbart publisher Boyle and Bannon.
The White House defended Miller after publishing the first set of e-mails, claiming that the Southern Poverty Law Center had launched an anti-Semitic attack on him. However, they did not address or defend the specific measures Miller took against Breitbart employees.
"The SPLC is involved in a vile slander campaign against a Jewish employee, while Mr. Miller condemns racism and bigotry in any form, denouncing him for denying his Jewish identity, which is a harmful form of anti-Semitism." said a White House official in a statement to CNN.
Hayden said he asked Miller for a comment almost a month ago.
He knew what was coming and he had time to prepare for it and that was all he could come up with because he knows the emails are his.
"Emails are emails," Hayden said. "The Southern Poverty Law Center works tirelessly against any hatred, including anti-Semitism."
Oliver Darcy and Mallory Simon of CNN contributed to this report.