An active message is an automated workflow step that has been marked as ready to send. When saved as active, anyone added to the group will get the message as determined by the scheduled timeline. If a message is not active, no one in the group can receive the message until it is made active. This allows you to have drafts of a message before it goes live.
To make it active, navigate to the Automated Workflow tab and then to the specific message you want to change the status of. Messages in the list with a red dot are inactive and will not send. Messages with a green dot are ready to send and will send as soon as someone in that group meets the scheduled timeline based off when they were added to the group.
To make an inactive (red dot) message active, click on the name of the message to open up the workflow step details. Once inside click Activate Step. This will set the message active. Activating a message will follow it's schedule and start sending immediately. If a person was added on the same day you make it active, immediate messages will only go if the message was active at the same time a person joined the group. If you activate a message that was set for a specific time of day (example 10am) and you make it active after that time, the message will not go that day.
You can now see that the message is active by the green dot indicating to you that it is set and ready to go when a person joins the group.
To deactivate just click on the message and hit the Deactivate Step button and you will be taken back to the workflow steps section for that group again.
You can reactivate and deactivate as much as you like, but keep in mind that the ones marked in red will not go out when a person joins the group, only the ones that are active and marked by the green dot.