Katherine Anderson Schaffner, one of the original singers from the iconic 1960s girl group the Marvelettes, has died at the age of 79. 

The Marvelettes are best known for their debut song "Please Mr. Postman," Motown's first number-one radio hit.

Schaffner's daughter told the Detroit Free Press that her mother - born Katherine Anderson - had been hospitalized with heart problems since July.

Marvelettes singer dies

The sad news was announced by Schaffner's daughter Keisha Schaffner over Facebook.

"Katherine Anderson Schaffner is and will always be one of the Original Marvelettes. Her music and Legacy will live on," she wrote.

"So the next time you hear ‘Please Mr. Postman,’ ‘Don’t Mess With Bill,’ or ‘The Hunter Gets Captured By The Game,’ just smile and say ‘I’ll Keep Holding On.’ Mom we love you and will miss you. And yes we know — ‘It is what it is.'”

Schaffner formed the group in 1961 with high school friends Gladys Horton, Georgeanna Tillman, Juanita Cowart, and Georgia Dobbins in the town of Inkster, a suburb of Detroit. They were discovered after performing at a high school talent show together, which led to an audition with Motown.

The group was offered a contract and they shed the name the Casinyets (a play on "can't sing yet") to became the Marvelettes. Dobbins, credited as one of the songwriters on "Please Mr. Postman," was replaced with Wanda Young.

Schaffner was a backing singer on their famous breakout track, which has been credited with putting Motown on the map. Horton sang lead and a then-obscure Marvin Gaye played drums on the recording, which was covered by the Beatles at the height of Beatlemania in 1963.

"We may have been from Inkster, but we kicked the door open for everyone else at Motown to walk through,” Schaffner told author Marc Myers for the 2016 book Anatomy of A Song. 

The Marvelettes continued to have touch-and-go success throughout the 1960s, with songs like "Twistin' Postman," "Playboy," "Don't Mess With Bill," and "Too Many Fish in the Sea," before breaking up in 1969.

American icon....

After the Marvelettes, Schaffner became a dedicated mom.

“Everything turned to her family. Music was behind her at that point,” Keisha Schaffner said. “She was always 100% attached to the Marvelettes, but she detached herself from Motown when they left Detroit (in the early 1970s).”

Schaffner is survived by her daughters Keisha Schaffner and Kalaine Schaffner Tamlin.

RIP to an American icon.