The message from May says, "He had skated on saying he has a Jewish heritage. I think I read he is an atheist. ... My Southern Baptist peeps would draw a big difference between a Jew and an atheist."
Sanders isn't actually named in the email, but in May, he was the only candidate with a Jewish heritage from either party. It's also not really clear if he's even an atheist.
See photos of Sanders when he was campaigning:
Bernie Sanders on the campaign trail
Bernie Sanders on the campaign trail
PHOENIX, AZ - MARCH 15: Democratic presidential candidate Sen. Bernie Sanders (D-VT) speaks to a crowd gathered at the Phoenix Convention Center during a campaign rally on March 15, 2016 in Phoenix, Arizona. Hillary Clinton won the Democratic primary elections in Florida, North Carolina and Ohio, while Missouri and Illinois remain tight races. (Photo by Ralph Freso/Getty Images)
DES MOINES, IA - JANUARY 26: Democratic presidential candidate Sen. Bernie Sanders (I-VT) speaks to the media after holding a campaign event with United Steelworkers Local 310L, on January 26, 2016 in Des Moines, Iowa. Sanders continues his quest to become the Democratic presidential nominee.. (Photo by Joe Raedle/Getty Images)
TOPSHOT - US Senator and Democratic Presidential Candidate Bernie Sanders speaks during a campaign event at the University of Northern Iowa in Cedar Falls, Iowa, January 24, 2016, ahead of the Iowa Caucus. / AFP / JIM WATSON (Photo credit should read JIM WATSON/AFP/Getty Images)
Senator Bernie Sanders, an independent from Vermont and 2016 Democratic presidential candidate, participates in the Democratic presidential candidate debate in Charleston, South Carolina, U.S., on Sunday, Jan. 17, 2016. Hours before Sunday's Democratic debate, the two top Democratic contenders held a warm-up bout of sorts in multiple separate appearances on political talk shows, at a time when the polling gap between the pair has narrowed in early-voting states. Photographer: Patrick T. Fallon/Bloomberg via Getty Images
NEW YORK, NY - JANUARY 05: Democratic presidential candidate Sen. Bernie Sanders (I-VT) shakes hands with supporters after outlining his plan to reform the U.S. financial sector on January 5, 2016 in New York City. Sanders is demanding greater financial oversight and greater government action for banks and individuals that break financial laws. (Photo by Andrew Burton/Getty Images)
LEBANON, NH - NOVEMBER 11: Presidential candidate Bernie Sanders (I-VT) marches in the Veterans Day Parade November 11, 2015 in Lebanon, New Hampshire. Sanders goes into the Democrats second debate this weekend still running strong in the polls.(Photo by Darren McCollester/Getty Images)
Senator Bernie Sanders, an independent from Vermont and 2016 Democratic presidential candidate, speaks at the Congressional Hispanic Caucus Institute conference in Washington, D.C., U.S., on Wednesday, Oct. 7, 2015. While next Tuesday's first Democratic presidential debate will probably lack the name-calling and sharp jabs of the Republican face-offs, there's still potential for strong disagreements between the party's leading contenders. Photographer: Andrew Harrer/Bloomberg via Getty Images
Democratic Presidential candidate Senator Bernie Sanders speaks about the Workplace Democracy Act on Capitol Hill in Washington, DC on October 6, 2015. AFP PHOTO/JIM WATSON (Photo credit should read JIM WATSON/AFP/Getty Images)
US Senator from Vermont and Democratic presidential candidate Bernie Sanders addresses striking low-wage contract workers from the US Capitol and religious leaders at the Lutheran Church of the Reformation in Washington, DC, on September 22, 2015 for an interfaith service ahead of the arrival of Pope Francis for a six-day visit to the US. AFP PHOTO/NICHOLAS KAMM (Photo credit should read NICHOLAS KAMM/AFP/Getty Images)
MANCHESTER, NH - SEPTEMBER 19: Democratic Presidential candidate Senator Bernie Sanders (I-VT) talks on stage during the New Hampshire Democratic Party State Convention on September 19, 2015 in Manchester, New Hampshire. Five Democratic presidential candidates are all expected to address the crowd inside the Verizon Wireless Arena. (Photo by Scott Eisen/Getty Images)
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"I would not be running for president of the United States if I did not have very strong religious and spiritual feelings," Sanders said.
But the idea that members of the DNC staff may have been plotting against a Democratic candidate is sure to piss off nearly everyone. Criticism of a "rigged system" to make sure Hillary Clinton was the nominee plagued the primary from the start. This is going to make it a lot worse.
And if Clinton and Democrats need anything as they head into their convention next week, it's not protesters yelling about a rigged nomination.
According to The Intercept, the author of the email says he doesn't remember the message but says, "It would not have been Sanders. It would probably be about a surrogate."