Question: We have a bad custom, which is the mixing of men with women. The reason is that we work with them in many occupations and look at them, and they do their work without their faces being veiled. We say that our intention is blameless, so someone of us will look at the face of his full brother’s wife and he considers her to be like his full sister, whom he is unable to marry, and he considers the wives of his neighbours to be in the same position as women he cannot marry. A man in our society lives with his full brother and his uncle’s son, and other members of his family with the men and women eating and drinking together. What is the ruling?
Answer: These matters belong to the customs of the first Jahiliyyah (the days of ignorance, prior to the start of the mission of Prophet Muhammad sallallaahu alaihi wasallam) and it is an obligation, according to Islamic Law, for the woman not to uncover her face except to those who are Mahrams for her. Similarly, it is an obligation upon a woman not to mix with men who are unrelated to her when she is unveiled, and it is also incumbent upon her not to be secluded in any place with a man to whom she is unrelated – that is, one who is not a Mahram for her. There is no doubt that mixing of men and women in the manner which you have described is in contradiction to the Islamic Law, because it causes an infinite amount of corruption. And Allaah is the Granter of success.
[Shaykh `Abdul-`Azeez Bin Baz – Fatawa Islamiyah, Darussalam, volume 5, page 137]