Avoiding Delayed Data

A data processing system for selectively transmitting data onto a network, the data processing system comprising: an application configured to form data for transmission and cause a timestamp to be generated and associated with the data for transmission; a network protocol stack configured to form the data for transmission into one or more network messages for transmission over a network connection, the one or more network messages being associated with the timestamp; and a delay determination unit configured to, immediately prior to the one or more network messages being transmitted onto the network by means of a network interface device, check the timestamp to determine the time elapsed from the time represented by the timestamp and, if the time elapsed is greater than a maximum period, cause the one or more network messages to be discarded.