Date: First day of Selichos 5581
From: Rabbi Moshe Sofer
To: Unknown recipient
The Chasam Sofer resolves a debate between the Beis Shmuel and the Noda BiYehudah's questioner by distinguishing the Bavli and Yerushalmi's approaches to mule identification: the Bavli requires both ears and tail not because one sign is insufficient, but to create a majority that can override the voice-sign, while the Yerushalmi rejects voice entirely as a divine contribution untraceable to either parent. This renders the proof from Chullin 79a irrelevant to the question of combining signs, leaving the Beis Shmuel's position that combined signs achieve siman muvhak b'yoser status intact.
Source: Shu"t Chasam Sofer EH I §59