Q. On a related matter, is it permissible for a mocher seforim to sell Mezzuzot to non-Jews who are trying to live as Bnai Noach?
Thank you,

A. See question above (1150). Remah (Y.D. 291: 2) rules that one should not sell a mezuzah to a Gentile unless there is a concern of creating enmity and promoting hate. Although Maharil prohibits even in such a situation, many Poskim side with the ruling of the Remah (Be’er Sheva 36, Sheilas Ya’avetz 2: 122, Yalkut Yosef – Kivud Av Vaem 6: 15)
Horav Shlomo Miller’s Shlit’a opinion is that one should avoid when possible selling mezuzos to Gentiles unless he is afraid he may be creating enmity as above mentioned or that he may be charged with a human rights violation. He should also be very alert and make certain that the buyer does not belong to a proselytizing cult that uses the mezuzos as a tool for attracting and perverting the uninformed. He should also make sure that the recipient is aware of the inherent holiness of the mezuzah and plans to use it with respect and decorum. The mocher seforim, may also want to inquire whether the Gentile buyer is not part of a mixed marriage or is a partner with a Jew on the property where the mezuzah is to be affixed.

Rabbi A. Bartfeld as revised by Horav Shlomo Miller Shlit”a