A method of tracing messages through a network of nodes is provided, the method comprising receiving message information corresponding to a first outbound message, the message information comprising a first source identifier and a first destination identifier and determining whether the first source identifier is associated with a set of messages in a storage unit, whereby when the first source identifier is associated with a set of messages, the method comprises producing a trace request, the trace request comprising the first destination identifier and an identifier identifying the set of messages associated with the first source identifier.