When you click a ‘edit settings’ or ‘preview email’ link in Slack, you’re taken to a browser page as we cannot show you this content in Slack. The link is secured and authenticates you. What’s more, it only grants access to a given page (e.g. one email).
Nevertheless, if you’re afraid these links might be shared, we can enable a special setting for your team: Users will be required to sign in with Slack before accessing any browser page. If you’re interested, send a Direct Message to MailClark to contact our support team.