A wireless messaging system includes a message controller and a delivery controller. The message controller provides a message to be delivered, and the delivery controller handles transmission of the message to a wireless device. To prevent delivery of a message after a desired expiry time or when a delivery window is closed, the message controller sends a cancellation request to the delivery controller. In response to the cancellation request, the delivery controller cancels any previously scheduled delivery attempts, and inhibits scheduling of future delivery attempts, at least temporarily.