When a user deletes their cookies, AdRoll remarketing loses the ability to track that user. Cookies are essential for identifying website visitors and showing them targeted ads later. Without cookies, AdRoll cannot recognize the user, which means they are removed from retargeting campaigns. To mitigate this, AdRoll uses cross-device tracking and email retargeting as alternatives. These methods rely on user accounts or email addresses rather than cookies. While cookies remain a primary tool, diversifying tracking methods can help maintain retargeting effectiveness even when cookies are deleted.