All emails designed in our email designer tool automatically have an opt-out (unsubscribe) link appended below the footer. This is not visible within the email tool, but will appear in both test emails and regular emails. This is what it says:
When a recipient clicks the link it will 1-click unsubscribe the recipient's email address.
If an email is forwarded and the 2nd person clicks the opt-out link, the original recipient's email address will be unsubscribed.
Note: Opt-out = unsubscribe. We often use these two words interchangeably, as they mean the same thing.