Is it permissible, Islamically, for a man to shake hands with a woman at work?

If the men are mahrams (unmarriageable kin), it is permissible to shake their hands; in fact, it is a Sunnah. However, if they are non-mahrams (strangers), it is not permissible to shake their hands, due to the Prophet's (peace and blessings be upon him) saying: "For one of you to be stabbed in the head with an iron needle is better for him than that he should touch a woman who is not lawful for him." There is no difference in the prohibition whether the person is at work or outside of it.