Inc.com columnist Alison Green answers questions about workplace and management issues--everything from how to deal with a micromanaging boss to how to talk to someone on your team about body odor.

A reader writes:

I'm a young business owner and new manager, and I could use your advice.

We recently had an employee (we'll call him Alex) resign to take on a new position. He left on a good note. While I was creating a backup of his company computer, I came across Skype conversations where he and a current employee (Jane) were ridiculing another employee ("Bob"). The conversations were (my opinion) unprofessional and childish. They mocked Bob at a professional and personal level: work quality, lack of knowledge, attempts at humor and social awkwardness, and even how loudly he chews were all targets. Bob does not, thankfully, know about these.

This happened during work hours over many months, on company machines, through Skype accounts set up for work use using work email addresses. Alex provided us with his password for Skype when he left.

A month ago, Alex and Jane brought up issues about Bob's work quality. Some of the issues were valid and we worked with Bob to improve things. Jane has mentioned that she's seen a difference (but kept on mocking him in private). Bob brings a variety of skills and value to the business. Other employees seem to value his experience and willingness to help. He's also stepped up, big time, to take on new responsibilities after Alex's departure.

I was already planning to have a conversation with Jane about her communication and treatment of coworkers, which two other employees (not Bob) have brought up. That conversation would have included a discussion about what was happening and why, clear explanations about what we wanted to see change, and an offer to provide tools or training to help her achieve them.

Should I bring up the Skype messages? She'll be mortified that what she said was seen, and I don't want to make her defensive. That said, and what she did is clearly bullying so I feel uncomfortable letting it slide.

Green responds:

Yes, you should bring it up.

Those were private conversations, but they were happening on company time using company resources, and in a medium that someone else ended up seeing in the normal course of business. They're fair game for those reasons -- and as her manager, you have an interest in not having your employees trash-talking each other.

If what you saw was just a little venting, I'd let it go -- but you're describing a cruel conversation that went on for months. And apparently there are already concerns about Jane's treatment of other coworkers as well.

It's worth saying something. I'd say it this way: "When I was cleaning up Alex's computer to create a backup of his files, I found conversations between the two of you mocking and ridiculing Bob. What I saw was extensive and mean-spirited, and seemed to go on for months. I'm dismayed at the cruelty I saw in those messages."

If she's mortified by this, that's a good outcome. Mortification won't destroy her, and sometimes it's warranted and useful.

And since this is part of a pattern with Jane, it sounds like you need to lay out very clear expectations of how she will and won't treat coworkers -- and then watch her closely enough for a while that you have a good feel for whether she's truly reforming or not.

Want to submit a question of your own? Send it to alison@askamanager.org.