Abstract: The disclosed embodiments relate to implementation, such as by a message processing system architecture, of a message handling system and/or protocol which mitigates optimistic messaging behavior. As used herein optimistic messaging behavior may at least refer to the transmission, in whole or in part, of a message, or of one or more messages of a sequence thereof, to a receiving system, such as the system implemented by the disclosed embodiments, prior to the sender determining that the message(s) is/are desired, alone or in conjunction with subsequently canceling or otherwise invalidating the message(s) once it has been determined that it is not desired. The disclosed embodiments mitigate such behavior by detecting and taking action with respect to these types of messages to deter optimizing behavior which may or may not be manipulative, while maintaining reliable message handling under increasing processing loads with minimal impact on users being able to send messages to the system.