Abstract: A service provider system may implement a notification service that manages actionable notification messages received from other services on behalf of a customer organization and its end users. An IT administrator of the customer organization may create and configure message inboxes to be maintained by the notification service. The messages stored in each inbox may be partitioned by source, type, targeted (authorized) recipients, or an associated message topic. Each message may include an identifier of the inbox to which it is directed, and active elements that, when selected by a recipient, cause a corresponding action to be performed. The service from which a message is received may, in response to a message recipient taking one of the available actions, submit a request to the notification service to update the message state. The notification service may provide APIs through which the other services and message recipients interact with the notification service.