Rav Shmuel Neiman, in Nine to Five: A Guide to Modest Conduct for Today’s Workplace writes regarding male-female interaction in the workplace:
It is forbidden to make small talk about matters unrelated to business. Men and women working together should not discuss politics, current events, recent tragedies or gossip, even if they do not do so regularly. Discussing these matters on a daily basis, is a violation of halachos that border on giluy arayos, which requires one to sacrifice his life rather than transgress. (p. 9)
When conversing with female employees or co-workers, one must be careful not to us the word “we,” so that the man and woman are not referred to as one unit. For example, one should not say, “We must talk with the editor,” or “We must purchase that software program.” Rather, he should say, “The editor must be consulted,” or “Please purchase that program.” (pp. 10-11)
It is a custom amongst yirei shomayim not to call a woman other than one’s wife or immediate family member by her first name, thus keeping a respectful distance between the two parties. Referring to a woman by her first name brings inappropriate familiarity into the relationship. Similarly, a woman should refrain from addressing a man other than her husband or immediate family member by his first name. (p. 20)
It is appropriate for male and female employees [to] refrain from all conversation when they meet anywhere outside of the office. This includes not discussing even job-related matters when meeting in the hallway or elevator at work.