Definition - What does Opt Out mean?
Opt out is an option for unsubscribing or leaving membership from a website, blog, group or any other online subscribed service. It is mainly used in email list management of online groups to provide subscribers with an option to withdraw their association from the email list, group or community.
Techopedia explains Opt Out
Opting out is the process of omitting a user from a subscription or mailing list. Once a user opts out, they no longer receive emails or messages from that list or website. On the website or list owner's site, the details of the person who opted out are deleted from the list, usually automatically through list management software. The opt-out rate is used in Internet marketing performance measurement to gauge the effectiveness of marketing and user retention activities and campaigns.