Administration queues contain acknowledgment messages generated by MSMQ for messages you send. These messages indicate that the messages you sent either arrived (a positive acknowledgment) or that an error occurred before the message could be retrieved (a negative acknowledgment). Positive acknowledgments indicate whether or not the message was retrieved by the target application. Negative acknowledgments indicate why the message was not retrieved.
The application programmer decides whether to use acknowledgments. If they are used, the application programmer must specify an administration queue in the source application and the type of acknowledgment messages to send to the queue.
Note Negative acknowledgments (NACKs) for encrypted messages are sent without the message body. Because only the destination computer can decrypt the message body, the message body is not useful on other computers.
For more information on administration queues, see the MSMQ SDK.