Someone who was experiencing a great number of difficulties phoned Reb Asaf Aharoni, one of Rabbi Eliyahu's assistants. Several people had suggested to this man that he get advice and help from Rabbi Eliyahu, who could sort out his problems.
The man asked Reb Asaf to approach Rabbi Eliyahu on his behalf. Rabbi Eliyahu, in turn, instructed Reb Asaf to ask this man about his mezuzot and see if he had checked them in recent times. The man replied that all the mezuzot in his home were new, good ones, but he said that since Rabbi Eliyahu told him to check them, he would.

The man took the mezuzot to be checked, and the scribe told him that they were kosher to the highest standard. He came back to Reb Aharoni with the answer and asked what he should do next. Reb Aharoni turned to Rabbi Eliyahu, only to hear him repeat that there was a problem with the mezuzot.
When Rabbi Eliyahu would check mezuzot himself, sometimes he would say, "This was written by a G-d-fearing scribe," and sometimes he wouldn’t say anything at all. When questioned as to how he knew who was G-d-fearing and who wasn’t, he replied, "I hold the parchment and I can feel it."
Yet, these mezuzot were being checked by someone else, so Reb Aharoni thought that perhaps the first scribe hadn't been enough of an expert. He sent the man to a scribe he knew and trusted, and the man paid to have his mezuzot checked for the second time.

The second scribe attested that the mezuzot were kosher to the highest standard. He also investigated who had written the mezuzot and found that the scribe from whom the man had purchased the mezuzot was a G-d-fearing Jew.
When the man came back to Reb Aharoni, he was understandably upset. He had now paid twice to have his mezuzot checked and each time he heard that they were fine. He felt that he had been fooled by those who called Rabbi Eliyahu a kabbalist. The man wasn't someone who was accustomed to going to rabbis for advice, and had only come to Rabbi Eliyahu because he had a number of problems. He then launched into a diatribe against rabbis…

Reb Aharoni began to worry that this whole incident could lead to a desecration of G-d's Name. He approached Rabbi Eliyahu to discuss it with him again.
Rabbi Eliyahu smiled. "Is it my fault that he hangs his mezuzot upside down?"
Reb Aharoni returned to the man and asked him to describe how he had hung the mezuzot. From his description, it immediately became clear that the man was indeed inserting them in their cases upside down, just as Rabbi Eliyahu had said.
Reb Aharoni explained how to properly hang the mezuzot, and the man thanked him profusely. But before he hung up, he inquired how Reb Aharoni had known he was hanging the mezuzot upside down. He answered that Rabbi Eliyahu had told him so.
The man was astonished. "How on earth did he know that my mezuzot were upside down?" he asked.
Reb Aharoni had no answer.