Though he lacked the reverence of the Rebbe's followers, he appreciated the opportunity to meet such a great man. When the arranged date came, he entered the Rebbe's study and handed him a note with his questions and requests, as he had been advised.
The Rebbe gazed intently at the piece of paper. "I recognize this handwriting. You have written to me in the past," he said.
The journalist was taken aback by this unexpected comment. "With all due respect," he replied, "I have never written you a letter."
The Rebbe sat in deep thought for a few moments. "There is no doubt that you have written to me in the past," the Rebbe maintained. As he spoke, he opened the drawer of his desk, took out a piece of paper and handed it to the journalist.
The journalist stared at the paper, stunned. Here it was, a letter to the Rebbe written in his own handwriting. But what is this at the bottom? Someone else had signed the letter.
Then he remembered. A few years earlier, during the Six-Day War, one of his buddies had injured his hand. After the war, the friend had wanted to send a letter to the Rebbe. Unfortunately, because of his injury, he was unable to write. The journalist wrote as his friend dictated, and the injured man managed to sign his name.
The journalist's attitude changed abruptly. The meeting became far more than a curiosity, and he departed far less indifferent than when he had entered.
In the seven years between the writing of that letter and that meeting, the Rebbe had responded to several hundred thousand other letters. Yet the Rebbe had this letter at hand.
[From Chabadworld.net]
[PS - I myself saw this story from an impeccable source].