Messages that are successfully processed by a node generate a signed acknowl- edgement message called a ‘receipt’. Note that this is distinct from the unsigned acknowledgements that live at the AMQP level and which simply flag that a message was successfully downloaded over the wire. A receipt may be generated some time after the message is processed in the case where acknowledgements are being batched to amortise signing overhead, and the receipt identifies the message by the hash of its content. The purpose of the receipts is to give a node undeniable evidence that a counterparty received a notification that would stand up later in a dispute mediation process. Corda does not attempt to support de- niable messaging