1. A notification system that reconfigures an electronic message to effect an enhanced notification, the system comprising: an input interface configured to receive at least one electronic message from a message source for delivery to an intended recipient; a definition store configured to store one or more notification definitions that include trigger parameters based on attributes of electronic messages including at least one of the message source and the message content; a matching engine configured to determine whether the electronic message is to be delivered with an enhanced notification by comparing the trigger parameters in one or more notification definitions in the definition store with corresponding attributes of the electronic message including at least one of the message source and the message content; a user information store configured to store information related to the intended recipient; and an enhancement engine configured to reconfigure the electronic message to the enhanced notification if the information of the user information store indicates that the intended recipient is subscribed to receive the enhanced notification.