18. The method of claim 14 , wherein outputting the priority comprises: determining an expected loss of non-review of the subsequent message at a current time; determining an expected cost of alerting the user of the subsequent message at the current time; and, alerting the user of the subsequent message upon determining that the expected loss is greater than the expected cost.
20. The method of claim 18 , wherein determining an expected loss comprises initially determining a current expected rate of lost opportunity as a function of present time.