a messaging system that handles messages of any kind , and a method of operation thereof , in which advanced messaging services can be implemented for multiple users , across multiple mail clients , in a more flexible and less limited fashion than previous messaging systems . the messaging system includes a plurality of messaging entities together having a state . an event supplier detects a change in the state of the messaging entities and generates an event announcement . an event manager receives the event announcement and generates an event notification . an event consumer receives the event notification and examines or manipulates at least one messaging entity .