In Slack, messages are shown when someone joins, is added to, or leaves a channel to let other members know who's coming and going. Workspace Owners and Workspace Admins can manage these messages and choose to turn them off if they'd like.
How join and leave messages work
Free, Pro, and Business+ plans
Enterprise Grid plan
By default, messages are shown when someone joins, is added to, or leaves a channel. Smaller groups might find these messages helpful, but larger groups might prefer to hide them. If you're a Workspace Owner or Workspace Admin, use the steps below to manage join and leave messages for your workspace.
Manage join and leave messages
From your desktop, click your workspace name in the sidebar.
Select Tools & settings, then click Workspace settings.
Scroll down to the Join & Leave Messages section and click Expand.
Check or uncheck the box next to Show a message when people join or leave channels.
Click Save.
If join and leave messages are turned off
👀Messages are displayed...
When someone joins or is added to a public or private channel
If someone leaves a private channel
🙈Messages aren't displayed...
When someone joins or is added to a public channel with more than 20 members
If someone leaves a public channel
If someone's account is deactivated
On Enterprise Grid, it's not possible to manage join and leave messages.
👀Messages are displayed...
When someone joins or is added to a public channel with less than 20 members or a private channel with less than 100 members
If someone leaves a private channel
🙈Messages aren't displayed...
When someone joins or is added to a public channel with more than 20 members or a private channel with more than 100 members