Team chat and messaging systems

Choose a team messaging system by checking whether the right people can discuss work, follow replies and find the outcome later. Compare a routine conversation and a restricted one using the plan and settings your team would use.

Decide what belongs in chat

Chat suits questions, updates and discussion while work is moving. Agree where approved decisions and the work they create will be recorded. Otherwise, a colleague returning from leave may have to reconstruct an outcome from several replies.

Map three common messages: an announcement, a project question needing several replies and a private matter for a limited group. Identify who needs to see each message and who needs to act.

Compare the conversation spaces

For Slack, test the conversation and reply structure your team would use, and check whether people can find the messages they need.

Before choosing a Slack plan, verify which message and file history will remain accessible and for how long.

Microsoft Teams has standard channels for the whole team, private channels for invited members and shared channels for selected people inside or outside the team. Channels can use Posts or Threads layouts. Teams is a candidate for organisations already working in Microsoft 365.

Adding people outside the organisation to a shared channel requires an administrator to enable B2B direct connect. Some guests, external users and people on older clients see a threaded channel in Posts layout instead.

For Google Chat, include a representative space in your test, and check whether its conversation and reply structure suits your team.

Chat is a candidate for teams already coordinating work in Google Workspace. Check the intended space settings: administrators control external access.

Test whether messages your team needs remain accessible under the history and retention settings in use.

Check whether messages can be found

For each candidate, try to find a project decision when you know the topic but not its author or date. Repeat as a colleague who missed the discussion. The result needs enough context to explain the answer, and that colleague needs access to it.

Then add several replies to a question while unrelated updates continue. Check whether participants can follow the replies and whether people outside the thread can find the resolution. A thread groups discussion; it does not identify an approved answer by itself.

Key retention and history limits across platforms

Match the audience before inviting people

Check who can discover a space, read earlier messages, post and invite others. If external collaboration is part of normal work, include the intended external account type in this check. An accepted invitation alone does not establish the full extent of that person’s access.

Give each restricted project space an owner who reviews membership when the work ends. Check separately shared files through their own permissions.

Check who can create and change spaces

Microsoft Teams standard channels are available to all team members, and posts are searchable by other team members. By default, any team member can create a standard channel, although an organisation owner can change that permission. Standard, private and shared channels cannot be converted into one another, so confirm the intended audience before creating a space.

Private channels require an invitation to view. By default, team owners and members can create them and add members, but guests cannot create private channels; an administrator can restrict who may create them.

For a shared channel, only team owners can create it, while shared-channel owners control adding members or sharing it with a team. Only its owners and members can access it.

For an external participant in a Teams shared channel, check that the required setup is in place: an administrator must enable B2B direct connect before people outside the organisation can be added. Include the actual external account and space type in the access test, rather than assuming that a successful invitation means every channel type will work.

Test what happens when external access changes

In Google Chat, an administrator can allow or block external messaging, and can optionally limit it to allowlisted domains.

Turning external chat off does not delete existing messages, conversations or spaces: already invited external users and guests can still see and access them, while users in the organisation can no longer access them. Their membership status does not change, and turning access back on makes those messages and spaces accessible again.

Removing external access to a Google Chat space does not itself prevent members from accessing data shared with that space, such as Google Drive files or tasks. If the aim is to prevent an external member accessing the space and its content, remove that person from the space. Check the relevant shared content separately, because changing access to the conversation is not the same as removing access to everything shared there.

Use these behaviours to test a real access change before adopting a system for external conversations: check what the invited external person can still see, what internal members can reach, and what happens to shared content.

In Google Chat, administrators can also see logged details of chat events initiated by outside users in conversations owned by the organisation, but cannot read the content from those events.

Record the decision

For each candidate, note the intended plan, required settings, retrieval result, reply behaviour, external access route and unanswered questions. Choose after the essential conversation and retrieval tasks work for the intended users.