An online photo management service that stores a collection of photos belonging to a user can send re-engagement messages to the user that can include photos automatically selected from the collection. The selection can be based on a scoring algorithm that rates the photos according to a set of attributes and computes a score based on the attributes and a set of weights. Based on user responses to re-engagement messages, the weights can be tuned to more reliably select photos likely to result in user re-engagement with the stored collection of photos.