A social networking system user identifies one or more social networking system users authorized to present content items to the user via the social networking system (“authorized users”). When an additional user requests presentation of a content item to the user, the social networking system determines if the additional user is an authorized user. If the additional user is an authorized user, the content item is presented to the user. However, if the additional user is not an authorized user, the social networking system identifies the additional user to the user along with a request to identify the additional user as an authorized user. If the user identifies the additional user as an authorized user in response to the request, the content item is presented to the user.