After working for the Pennsylvania State Relief, teaching, and attending what is now the New York Theological Seminary, Mary went to Egypt in 1939 as a missionary for the Presbyterian Church and became a teacher at the American Mission School in Tanta.
The authority of the Chief Rabbinate of Cairo extended to the Jewish communities of Port Said, Mansoura, Banha and Mit Ghamr, whereas Tanta, Damanhur and Kafr El-Zayat were under the jurisdiction of the Chief Rabbinate of Alexandria.