Slack messages, threads, and attachments are searched the same way as other Social Media content — see How to Search for Social Media Content. 

On the Social Media Search tab:

Account (first dropdown) — select the Slack workspace(s) you want to search, alongside any other connected social accounts.

Content Type (second dropdown) — Slack offers Message (covers both channel messages and thread replies), Photo, Video, Audio, and Document.

Search criteria (third dropdown) — the same fields as other Social Media Search: From, To, Chat Name (the Slack channel name), Message Content, Attachment, Tags, Notes, and Status.

Once you run a search, results are listed with the Slack icon, content type, channel name (shown as Message (#channel-name)), the message itself, and the date/time.

Click a result to open its Single Result View on the right:

• The header reads Slack Conversation and the channel name in brackets.
• Below the header, you'll see either the channel name, or, if the result is a thread reply, Thread initiated by followed by the name of the user who started the thread.
• Messages are then listed the same way as Microsoft Teams results — see How to View a Single Microsoft Teams Search Result for how edited and deleted messages are presented.