Today a user asked a question in a private team (visible only for colleagues in our department) in MS Teams. This question referred to the rollout of a product. I needed some more information and messaged this user in private in MS Teams. After getting the information I also provided the answer in this private chat.
An hour later this user posted a screenshot of our private conversation in a different private team. He also added a slightly negative comment on how the rollout is planned.
I know that the chat history in personal apps like WhatsApp is confidential and cannot be shared without the consent of all involved (at least in my country, Germany). Does this also apply to business apps like Teams/Slack or even just the Outlook email history between two people?