Boss choosing a female secretary for the workplace
Question

                My question is: is it permissible for a woman to work as a secretary for a service company, knowing that the company’s office consists of two rooms and a reception area, and the owners of the company are of good character and religiously-committed. Their reason for choosing a girl to work there is that this is the custom in our country, in addition to the fact that she is more capable in secretarial skills and using the computer. 

Is there any sin on the company owners because of this, and is it permissible to work so long as they adhere to modesty and religious dictates? Is it permissible for them to employ a female worker to clean the offices etc?  

I hope that you can explain, with evidence: is there a difference between khulwah (being alone with a member of the opposite sex) and ikhtilaat (free mixing)?.
Praise be to Allah.
    Firstly: 

    It is not permissible for a woman to work in a place where 
    she will mix with men, because of the bad consequences and haraam things 
    that this leads to, such as khulwah (being alone with a member of the 
    opposite sex), looking, shaking hands and becoming attached to bosses and 
    colleagues, and other things that are well known. Hardly any mixed workplace 
    is free of these haraam things. 

    We have already quoted the evidence for mixing being haraam 
    in the answer to question no. 1200. 

    Secondly: 

    It is not permissible for bosses to employ a woman to work 
    among men, whether as a secretary, cleaner, or anything else, because that 
    is helping in haraam mixing. 

    The fact that this is the prevalent custom in a country does 
    not serve as a justification for it in terms of sharee’ah, rather customs 
    must give way to shar’i rulings and are subject to them .  

    The claim that women are better at secretarial skills and at 
    using the computer is not true. There are also men who are good at these 
    skills, and the matter depends on making a good choice. Men are more 
    entitled to jobs because it is the man who takes care of the family and he 
    is the one who is required to spend on them according to sharee’ah. If a 
    woman is able to find work that is free of haraam things, she may do that, 
    otherwise her house is better for her. 

    Thirdly: 

    It is haraam for a man and woman to be alone together, 
    because the Prophet  (peace and blessings of Allaah be upon him) said: 
    “No man is alone with a woman but the shaytaan is the third one present.” 
    Narrated by al-Tirmidhi (2165); classed as saheeh by al-Albaani in Saheeh 
    al-Tirmidhi. And he  (peace and blessings of Allaah be upon him) 
    said: “No man should be alone with a woman without there being a mahram 
    present, and no woman should travel unless she has a mahram with her.” A man 
    stood up and said: O Messenger of Allaah, I have enlisted for such and such 
    a campaign and my wife has set out for Hajj. He said: “Go and do Hajj with 
    your wife.”

    Narrated by al-Bukhaari (3006)and Muslim (1341). 

    What is meant by “being alone” is that they are together in a 
    place where no one else can see them. 

    With regard to mixing: it may be without khulwah (being alone 
    together), such as when a number of men are together with a number of 
    females. What is haraam is that which leads to any of the haraam things 
    mentioned above, such as looking, touching, speaking in a soft alluring 
    voice, and forming attachments. This – as stated above – is hardly absent in 
    any mixed workplace, because people meet so often and sit together for 
    lengthy periods. This breaks down all barriers, especially in small or 
    confined spaces with a limited number of people, as in the case mentioned in 
    the question. In this case the opportunities to get to know one another and 
    become attached are even greater. 

    Mixing may be free of khulwah, but it does not prevent making 
    appointments to meet elsewhere, and things that are worse than that. 

    Whoever studies the evidence for mixing being haraam – which 
    is quoted in the answer referred to (no. 
    1200) – will understand the wisdom 
    behind Islam closing the door to it, and will understand that this command 
    is based on an understanding of the nature of both sexes and what results 
    from their being close together. Islam is keen to protect both of them.  

    It says in Fataawa al-Lajnah al-Daa’imah (12/156): 
    Mixing between men and women in schools and elsewhere is a great evil and 
    adversely affects religious commitment and worldly interests. It is not 
    permissible for a woman to study or work in a place where men and women mix, 
    and it is not permissible for her guardian to allow her to do that. 

    May Allaah help us all to do that which He loves and which 
    pleases Him. 

    And Allaah knows best.