1. A computer-implemented method comprising: operating a computer to perform acts comprising: receiving a first message; detecting user input indicating one of a plurality of actions with respect to the first message; training a classifier based on the received first message and the detected user action; receiving a second message; generating a priority of the second message with the classifier, and outputting the priority, wherein outputting the priority comprises: determining an expected loss of non-review of the second message at a current time; determining an expected cost of alerting the user of the second message at the current time; and, alerting the user of the second message upon determining that the expected loss is greater than the expected cost.