FrontSpin connects to a user’s own email account (e.g. Gmail, Outlook, etc.) and therefore does not a direct unsubscribe option.
What is commonly done to add an unsubscribe option is to simply include that language in the user’s email footer (e.g. “reply UNSUBSCRIBE to opt out”) and then the user would opt them out in FrontSpin or Salesforce by using the Email Opt Out field checkbox.
The Email Opt Out field is a standard field in Salesforce and can be mapped to FrontSpin under SETTINGS > INTEGRATIONS > MAPPING, and then added to the user’s Page Layout in FrontSpin under SETTINGS > YOUR ORGANIZATION > LAYOUTS.
Finally, with regard to the Salesforce Reports powering your Lists/Playbooks in FrontSpin, you would need to include the criteria/condition “Email Opt Out = False” so that once checked, the prospect would be automatically removed from that List/Playbook.