Embodiments of the invention are concerned with modification of messages en route to a destination.In one aspect embodiments of the invention provide a method of modifying a message transmitted from a sending party to a receiving party through a communications network, the method comprising: intercepting the message in the communications network; selecting a plurality of channels of data on the basis of the sending party or the receiving party, each channel comprising a plurality of data items and being accessible by parties in addition to the sending party or the receiving party; applying one or more predetermined rules to at least some of the selected data items so as to identify a data item therefrom; and appending data derived from the identified data item to said intercepted message.