First recorded by The Moonglows (US#20/R&B #1 1955).
Other hit versions by The McGuire Sisters (US #1/UK #14 1955), The Forrester Sisters (C&W #8 1989).
From the wiki: “Among the most seminal R&B and doo-wop groups of all time, The Moonglows’ lineup featured some of the genre’s greatest pure singers. The group were originally called ‘The Crazy Sounds’, but were renamed by radio disc-jockey Alan Freed as ‘The Moonglows’. (The group also cut some recordings as The Moonlighters.) Their first major hit was the #1 R&B gem ‘Sincerely’, for Chess Records, penned by group member Harvey Fuqua and recorded by them in late 1954.
“The best-selling version was a pop cover recorded by The McGuire Sisters, entering the charts in January 1955 and reaching #1 shortly thereafter. Many R&B collectors decry that the cover version by The McGuires kept the Moonglows from peaking higher than it did on the Pop chart, limiting its success to the Billboard Top 20.
“The Moonglows would go on to score five more Top 10 R&B hits in the 1950s, including ‘Please Send Me Someone to Love’ and ‘Ten Commandments of Love’ (as Harvey & The Moonglows, with Marvin Gaye as a group member). Fuqua would go to found his own record label, Tri-Phi, create and produce The Spinners in 1961, introduce Marvin Gaye to Berry Gordy, and write and produce for Motown Records until the early ’70s. The Moonglows were inducted to the Vocal Group Hall of Fame in 1999 and, in 2000, to the Rock & Roll Hall of Fame.”
The McGuire Sisters, “Sincerely” (1955):
The Forrester Sisters, “Sincerely” (1955):