Slack: How To Disable Public File Sharing
Slack is a channel-based communications app that allows members of workspaces to communicate. Each workspace is technically invite-only, however, if it is public, the workspace might be configured differently. It can be set up to pre-accept any invites/requests to join for popular email providers. Realistically though, most workspaces require an invite to join. For corporate workspace, you typically have to be an employee or contractor to have access. That said, some companies may have shared channels with other companies they regularly work with....