Message Delivery System and Method

In one embodiment, a method of delivering messages to a user of a user terminal executing a communication client and connected to a packet-based communication network, includes receiving a message at the communication client from the communication network, the message comprising a content portion and a control portion, wherein the content portion comprises information intended for display to the user of the user terminal, and storing the message in a data store at the user terminal. The communication client reads the control portion of the message and extracts data defining a trigger event and a condition. The communication client is monitored to determine whether the communication client state corresponds to the trigger event. Responsive to the communication client state corresponding to the trigger event, the communication client determines whether the condition is met. In the case that the condition is met, the content portion of the message is displayed in the communication client.