Opt-out results in a profile no longer being targeted by any delivery or by deliveries from a specific channel.
To give profiles the ability to opt in or opt out, you have to create a dedicated landing page. For more on this, refer to Setting up opt-in and opt-out landing pages.
Profiles can also be opted in or out manually by an operator. For more on this, refer to Managing opt-in and opt-out from a profile.
Opt-out profiles are automatically excluded during the delivery analysis in order to speed up deliveries (the error rate has a significant effect on delivery speed).
Opt-out applies to Profiles, as opposed to quarantine which is linked to an email address or phone number. Opting out a profile will therefore exclude from deliveries all the addresses linked to it. If a user has two profiles in the database, he will still be targeted by deliveries as only one of his profiles is opt-out. To make sure all his adresses are excluded, add them to the quarantines addresses. For more on this, refer to this page.
For more on services subscriptions, refer to this page.