User-Agent: Slackbot-LinkExpanding 1.0 (+https://api.slack.com/robots)
Disallow:

User-Agent: Slack-ImgProxy 0.19 (+https://api.slack.com/robots)
Disallow:

User-Agent: Slackbot 1.0(+https://api.slack.com/robots)
Disallow:

User-Agent: *
Disallow: /