You can setup a campaign to kick-off as soon as someone's appointment/reservation is over by following these steps:
Login to the PeopleVine Control Panel
Build the e-mail that will go out as soon as the campaign is triggered
Then go to Automate > Campaign > New When It's Over Campaign
Enter the details about this campaign
Select the activity to be completed, this will trigger the message to go out
Set how long after the activity is over before sending out the email
Select the email to send out once this campaign is triggered.
Now after someone's appointment is over, PeopleVine will automatically send them a follow up email for next steps.