When a customer receives your campaign via email, there will be an option to unsubscribe.

That link will bring them to this screen: https://lab.alpineiq.com/emailSettings/{{storeID}}

Currently, it's just one option to opt-in/out of all communications, as seen in the screenshot below:

Campaigns sent via Text will have the text Reply STOP to opt out appended to each message. Customers can type stop and send a message to that same number and they will be opted-out of text communications.