Once you've created and set up your recall campaign(s), you'll be able to keep track of their reach and status by going to Messaging > Monitor Campaigns.
It will list all current campaigns set up and have the following columns:
When you expand a line item, more columns will populate.
What each status means -
Sent: Confirming that the message did get delivered all the way through.
Opened: Whether or not the client sent to opened the actual email.
Clicked: If they clicked on the action item within the message itself.
Completed: Whether or not they completed the action item to book their next appointment the trigger was set up for.
If you select 'view' for the corresponding line item, it will give you the specifications of the trigger that were in place for that to be sent, including any future scheduled events and a copy of the message they received.