To allow a third party system to more particularly identify sets of users for distributing content, an online system receives data from a third party system identifying users of the online system who have authorized communication with the third party system and stores information authorizing communication between the third party system and the users in user profiles associated with the user. The online system receives a request from the third party system to transmit a notification to online system users satisfying criteria specified by the request. User profiles including information authorizing communication between the third party system and online system users are identified by the online system, which selects a set of the identified user profiles associated with information satisfying the criteria specified by the request. The online system transmits the notification to client devices associated with users associated with the set of the identified user profiles.