"The prevalent view of the jurisprudents is that sexual intercourse of any kind is not permissible with Zoroastrian or idolatrous women. According to some, a Muslim who has intercourse with such a woman is (from the religious view point) not better than the infidel woman herself. This being so, most fuqaha maintain that women belonging to these groups should embrace Islam before any intercourse can take place. If they refuse, they are used as servants, but sexual intercourse with them is not permitted. This is evidently not an optimal solution, and numerous traditions maintain that women who refuse to embrace Islam willingly should be subjected to coercion."
January 1, 1970
https://en.wikiquote.org/wiki/Women's_rights_in_Iran