1. An adaptive mobile device notification system comprising one or more computing devices programmed to: send a notification messages to a plurality of mobile devices, wherein content of the notification messages is selected using a modifiable ruleset maintained by the adaptive notification system, and wherein the notification messages each include an identifier that uniquely identifies the message; receive session data from the plurality of mobile devices in response to the notification messages, wherein the session data includes session details relating to user engagement with the notification messages, wherein the session details relating to user engagement on at least one of the plurality of mobile devices are recorded directly by an application on the at least one mobile device and include an indication of whether the application was launched within a predetermined time period of receipt of the notification message; and perform an automatic modification of the ruleset based at least in part on the user engagement with the notification messages, wherein the ruleset includes at least one delivery parameter, the delivery parameter chosen from the group consisting of an identity of a user of the mobile device, type of mobile device, a cohort of users sharing a property or behavior, frequency of notification, time of day, location of the mobile device, day of the week, and textual or media content of the notification message.