Is Microsoft Teams safe for confidential business conversations?

Safe against what? "Safe" only means something once you name the adversary.

• Against opportunistic attackers on the network: yes. TLS everywhere, strong identity controls, conditional access.
• Against credential theft: largely, if MFA and conditional access are configured well.
• Against a party who can read platform-side content: no, by design. Governance and assistant features require the service to read content.

Which conversations to reconsider Move the conversation elsewhere when disclosure would be materially harmful and the participants are a small, known group:

• deal terms, valuations and negotiation strategy
• privileged legal advice and matter discussion
• patient or client identifying details
• security incident response
• unreleased product, source code and creative work under NDA
• HR investigations

Keep on the governed platform anything subject to tenant-wide retention or supervision obligations. That separation is defensible; a blanket move is not.

The three questions to ask internally 1. If our provider were compelled to produce this channel's content, what would they be able to produce? 2. If a tenant administrator account were compromised, what content becomes readable? 3. When someone leaves, does anything cryptographic change, or only a permission?

What "somewhere else" should look like Not a consumer messenger bolted onto the side. The confidential surface needs the same working patterns — channels, threads, file drops, calls, search — or people will drift back. It also needs a real encrypted drive, because conversations produce files.

In DRIVUNO, messages and attachments are sealed on the device under a room key wrapped per member, files live in an encrypted drive with client-side previews, search runs on blind indexes built locally, and external sharing uses passphrase-gated links that expire within 24 hours at most.

The honest caveat Endpoint security still matters. If a participant's laptop is compromised, encryption in the platform does not save the conversation. Zero-knowledge narrows the attack surface to the endpoints — which is exactly where you can apply device management, disk encryption and hardware-backed keys.