title: Zapier Slack Private Channel: Only send message if user is in channel
body: <p>I have a very simple Zap that is triggered when my team’s CRM detects an issue with a customer (e.g. an automated email campaign bounced). Using the CRM data, the Zap finds the customer’s assigned consultant in Slack, then sends a private channel message to our bouncelog, @ mentioning the consultant and giving a link to the customer’s info. Unfortunately, we recently started having issues where the Zap is being triggered for customers with consultants that aren’t part of our team, and therefore aren’t members of this channel. The Zap still tries to @ mention them, which causes problems on the Slack channel.</p>
  <p>Is there a way to look up the members of a Slack channel to use in a filter/code step? Or some other way to make sure this Zap doesn’t try to @ mention users who aren’t in the channel?</p>