title: Subscribing an User to a Thread using the Slack API
body: <p>This is the first question I ask in quite a few years :-)</p>
  <p>I've gotten to play around with the Slack API recently to write up some notification bot.
  As part of the bot workflow, I want it to send messages to a channel, where it will create a thread based on the initial message.</p>
  <p>This is done already, by using the <code>chat.postMessage</code> verb and <code>thread_ts</code> attributes. However, messages to threads that an user is not involved or subscribed to will not send any notifications.</p>
  <p>My question, is it possible to have a a bot subscribe you to a thread? This is explained <a href="https://slack.com/intl/en-es/help/articles/115000769927-Use-threads-to-organize-discussions-" rel="nofollow noreferrer">in this Slack KB post</a>, where you can manually sign in to notifications using the three dotted menu, or by pinging the user.</p>
  <p>My initial idea is based on the Block Kit interface, where clicking a button would subscribe you to the channel, providing more visibility than the three dotted menu approach. Is this something feasible?</p>
  <p>I haven't found any reference to this on the <a href="https://api.slack.com/methods" rel="nofollow noreferrer">Slack API method Reference</a>, but perhaps it's hidden somewhere else.</p>
  <p>As a fallback mechanism, I will think on editing the original message with a list of &quot;subscribers&quot; so that they will notified of updates to the thread.</p>