In one embodiment, a method includes one or more computing devices detecting a triggering action by a user of a social-networking system, wherein the detecting includes receiving information about the triggering action from a client device associated with the user and accessing a queue including multiple notifications. The method also includes, for each of one or more of the notifications, calculating using a machine-learning model, a click-through probability that the user will interact with the notification upon display of the notification, wherein the machine-learning model is based at least in part on one or more features associated with the user or the notification, determining whether the click-through probability satisfies a threshold, and if the click-through probability satisfies the threshold, then sending the notification to the client device associated with the user for display, else, removing the notification from the queue.