Q. How should I handle a colleague who constantly eavesdrops on my conversations?
N.S., Eugene, Ore.
A. You have three choices: do nothing, confront the eavesdropper immediately, or talk to the eavesdropper at a time other than when the eavesdropping is taking place.
If the eavesdropping is just a minor annoyance, you'll need to decide whether it's really an issue you want to confront the eavesdropper about or whether you can deal with it some other way -- such as suggesting to the person you're talking with, "Jane, let's move to a conference room to continue our conversation."
If you decide the situation warrants action, you could try saying something at the moment the eavesdropping occurs: "Tom, I couldn't help noticing that you're listening to our conversation. Would you mind giving us a little privacy? We'd really appreciate it."
The problem with this approach is that Tom may react badly, in which case your conversation could deteriorate.
The preferred solution is to speak to the eavesdropper later, in private: "Tom, I asked to talk with you because something's happening that's making me uncomfortable. I've noticed that sometimes you seem to be hanging around listening in on my private conversations. Could I ask you to give me some space in these situations, so I can talk without being overheard? Other times, when it's not a private conversation, I'll make every effort to include you. Is that OK with you?" (source)