The next time you start typing your boss's email address in the CC field on an email chain with your coworkers, you might want to reconsider. It could affect how much your colleagues trust you. As University of Cambridge researcher David De Cremer writes in the Harvard Business Review, adding supervisors to office email chains reduces trust between employees.

The study by De Cremer and his colleagues is still under review and unpublished, but in his HBR piece, he discusses the results of his six experiments with around 600 participants from both the U.S. and China. In surveys, participants reported feeling significantly less trusted by their colleagues if their supervisor was always copied on their email communications.

And the feelings of mistrust don’t just apply to specific colleagues, but to the workplace at large. “My findings indicated that when the supervisor was copied in often, employees felt less trusted, and this feeling automatically led them to infer that the organizational culture must be low in trust overall, fostering a culture of fear and low psychological safety,” he writes.

That’s not to say that you should never use that CC button, but be aware that for your coworkers, it could be seen as a “potentially threatening move,” as De Cremer puts it. While some people might unintentionally slight colleagues by CC-ing the supervisor, many of the participants in the experiments knew the effect it would have on the email’s recipient, indicating that people may be strategically CC-ing as a power move.

It turns out, extreme transparency isn’t always the best thing for offices. Some exchanges your boss just doesn't need to know about—for the good of the company. Time to brush up on your email etiquette, anyone?