Working with clients and contractors in Teams: guests, external chat and shared channels

External chat: talking to other organisations

External access lets your staff find and chat with people at other organisations that use Teams, using their normal work accounts. It works like an internal chat: one-to-one or small group conversations, calls and presence. It suits a quick question to a supplier's account manager or a regular contact at a client. There is no access to your files or teams, so the risk is low.

Administrators can allow external chat with all organisations, only specific domains, or none. Many small businesses allow it broadly, while others list only known partners. Whichever you choose, train staff that a chat request from an unfamiliar organisation deserves the same caution as an unexpected email, because attackers have used Teams messages to deliver malicious links.

Guest access: bringing someone into your team

A guest is an outside person given access to a specific team in your organisation. They sign in with their own email address and see only the teams they are invited to. Guests can take part in channel conversations, open and edit files in that team, and join meetings as a team member. This suits a contract bookkeeper who works with your finance team, an architect collaborating on a building project, or a client reviewing deliverables.

The practical downside is switching. Guests must switch between their own organisation and yours in Teams, and notifications from the guest organisation can be easy to miss. For people who work with you every day, that becomes annoying. For occasional collaborators, it is perfectly workable. Before inviting a guest, think about which team they are joining. A guest added to a big general team sees everything in it, which is rarely what you intended. It is common to create a small team just for the work you are doing together, so the boundary is clear from the start and nothing internal is exposed by accident.

Shared channels: working across two organisations

Shared channels let a channel appear inside both organisations' Teams without anyone switching. Each person uses their own account and sees the shared channel alongside their usual teams. Both organisations need to allow this in their settings, which takes some coordination with the other party's IT. When it is set up, it offers the smoothest experience for ongoing partnerships, such as a joint venture or a long-term outsourced function. Because it needs agreement on both sides, shared channels are best reserved for relationships expected to last months or years. For a three-week job, guest access or a shared folder is quicker to arrange.

Settings to check before inviting guests

Guest settings live in several places: the Microsoft 365 admin centre, the Entra identity settings, SharePoint sharing settings and Teams itself. If guests cannot be added, one of these is usually blocking it. Decide as a business who is allowed to invite guests. In many small offices, team owners can invite guests to their own teams, which is reasonable as long as owners understand the responsibility. Check what guests can do once inside. You may not want guests creating channels, deleting messages or sharing files outside the team. Require guests to complete multi-factor sign-in, which you can enforce from your side even if their own organisation does not.

Keeping sensitive information separate

A guest in a team can see every standard channel and every file in that team. Do not invite a client into your internal operations team where staff discuss pricing and margins. Create a dedicated client team, or use a shared channel, containing only what the client should see. Sensitive internal discussions about that client happen in a separate internal channel.

Label external teams clearly, for example with Client - Harbourview Apartments in the name, so staff can see at a glance that outsiders are present. Teams also shows a notice in chats and channels where external people are included; make sure staff pay attention to it before posting. Also think about the other direction. When your staff are invited as guests into a client's Teams, the files they work on live in the client's environment under the client's rules. Keep your own copy of anything you need for your records, because when the client removes guest access, those files disappear from your view.

Cleaning up guest accounts

Guests accumulate. Two years after a project ends, the architect, the old bookkeeper and a client's former staff may still have access to your files. Set a regular review, quarterly is sensible, to remove guests who no longer need access. Business Premium and some other plans include access reviews that ask team owners to confirm each guest, which makes this easier. When a project finishes, archive the team so it becomes read-only and remove guests at the same time. Under the Privacy Act 2020, you are responsible for who can access personal information you hold, including outsiders you invited in years ago. A short end-of-project checklist covers it.