A method for message delivery to a transaction processor is presented. The method may include receiving a message having transaction information. The method may also include determining if the received message is prohibited from delivery based on comparing the transaction information with a blacklist, wherein the blacklist is used to block messages. In response to determining that received message is prohibited from delivery, the method may then include refusing message delivery or delaying message delivery. In response to determining that the received message is not prohibited from delivery, the method may further include enqueuing the message in a request queue. The method may also include receiving a reply message with a transaction status update from the transaction processor. The method may then include updating the blacklist based on the received reply message with the transaction status update.