Short answers, pulled from the story.
The Stalin Note, also called the March Note, was a document the Soviet Union delivered to representatives of the United States, Britain, and France on the 10th of March 1952. It proposed reunifying Germany as a neutral state, with occupation forces withdrawn and democratic freedoms guaranteed.
Andrei Gromyko delivered the Stalin Note on behalf of the Soviet Union to representatives of the United States, Britain, and France on the 10th of March 1952.
Konrad Adenauer prioritized binding West Germany to the Western Alliance over reunification and doubted the Soviet offer was sincere. He also worried that readmitting East Germany's 18.5 million citizens to the voter rolls would pull West Germany's 51 million citizens politically leftward.
East Germany received the note with official excitement. Its party newspaper, Neues Deutschland, declared that the Soviet Government was giving patriotic forces the chance to fight for peaceful reunification, and Prime Minister Otto Grotewohl framed West Germany as undemocratic in a declaration on the 14th of March.
The Soviet Union sent four notes between March and August 1952, on the 10th of March, the 9th of April, the 24th of May, and the 23rd of August. The Western Powers answered each one, and the exchange ended without a peace conference.
Historians remain divided. The publicist Paul Sethe and historians including Rolf Steininger argued a real chance was missed, while others cited East Germany's strategic value to Stalin and argued the offer was not genuine.