How can my customers unsubscribe from campaign emails?
Including "unsubscribe" links is not required (or recommended) in Churn Buster emails. Churn Buster only sends transactional emails — delivered on a per-customer basis (never "in bulk" to a list) for the sole purpose of resolving a payment issue.
Customers opt out of receiving dunning emails when their subscription is deactivated or payment method is updated.
If a customer requests to stop receiving campaign emails, you can manually stop a campaign.