hudi — Yasher Koach for being proactive about this area. It is so easy to underestimate the risks involved in a situation like this. As far as the negiah goes, I think mytake’s approach is very sensible. Sending out a mass email makes it into an issue. I think you are much better off explaining as the need arises, in a very matter of fact way.
As far as the bigger issue, I think that some on this thread are misunderstanding “cold”. It doesn’t seem that anyone is advocating rudeness. What is appropriate, however, is to come across as slightly reserved and private. Actually, that is very much a part of professionalism. It is not “professional” to mix personal life with your profession. One may choose to have both a personal and professional relationship with others, but that is a choice, not a requirement, and one who chooses not to do so is not being rude.
When I worked in the secular work place the men I worked with knew that I had no problem answering work related questions, helping out with something they needed guidance on, etc. But when the conversation turned to personal life, I was quiet. Not rude, but just nonresponse or short to the point responses. No one perceived me as rude — just as a private individual. They get the feeling very quickly. (I was married, and they were aware of it, but I don’t think that is enough in today’s world in any case.)
Additionally, they usually pick up very quickly that you have different standards. I often had co-workers apologize to me after using nivul peh in front of me — they’d look up and notice I was around and kind of get red and say “oh, sorry!” and I would just give a small smile and nod. I never said anything to anyone about nivul peh, but they understood instinctively that as a frum woman my standards were different.