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. However, if a user has two profiles in the database, this user will still be targeted by deliveries as only one of their profiles is opted out. To make sure all their addresses are excluded, add them to the quarantined addresses. For more on this, refer to this page.
For more on services subscriptions, refer to this page.