The modification of a network message so that a supplemental action is performed in transit at a designated intermediary node. The modification is performed in a manner that is transparent to the source computing entity that caused the network message to be generated. Upon acquiring the network message, a message modification component modifies the network message so that the network message is routed through an intermediary node, and further so that the intermediary node performs supplemental action(s). For instance, the modification might cause routing components to route the network message to the intermediary node, and the modification might also include instructions that the intermediary node interprets as being an instruction to perform the supplemental action.