Meta added exclusion-only custom audiences, a customer list that can keep people out of an ad set but can never be used to target them. The setting is a one-way door, since an exclusion-only list can’t be converted into a regular custom audience once it exists, which makes it a permanent guardrail against someone getting swept back in through another list. Meta names two uses, suppressing promotions for people who have opted out of a business’s products and honoring legal or regulatory obligations not to target certain individuals. Jon Loomer suggests a third, dropping employees out of the audience so advertisers quit paying for impressions that were never going to convert.
