A summary of known facts is occasionally useful in this matter:
6) also in July Pavel Manafartov emailed Konstantin Kilimnik to offer private briefings to Oleg Deripaska. On July 29, a week after Trump accepted the Republican nomination, Manafartov received an email from Kilimnik, this one with the subject line “Black Caviar.” “I met today with the guy who gave you your biggest black caviar jar several years ago,” Kilimnik wrote. “We spent about 5 hours talking about his story, and I have several important messages from him to you. He asked me to go and brief you on our conversation."
On July 31, Kilimnik and Manafartov corresponded again to firm up their plans for a dinner meeting in New York on August 2 at the Grand Havana Club. “I need about two hours,” Kilimnik wrote to Manafort on July 31, “because it is a long caviar story to tell.”