Open the message within the app.

You can reply to a message by pressing on the message you want to reply to and press “Reply in thread”. If a reply already exists you can add to the thread.

Replying to a message in a thread means notifications are only sent to the original poster, and anyone else who has replied in the thread.

IMPORTANT: DO NOT reply to messages from the notification on your lock screen – this creates a new post. Instead open the post properly and then reply. See below. (We’ve asked Slack to change this behaviour)