Acknowledgment Messages

An acknowledgment message indicates a positive or negative acknowledgment. The following table lists the message properties that have special meaning when attached to an acknowledgment message.

Note Connector applications must set these properties when sending positive (including read receipt messages) and negative acknowledgment messages back to the sending application.

Message Property (ActiveX property)	Setting
PROPID_M_ACKNOWLEDGE (Ack)	None.
PROPID_M_ADMIN_QUEUE (AdminQueueInfo)	Null.
PROPID_M_APPSPECIFIC (AppSpecific)	Same as original message.
PROPID_M_BODY (Body)	For positive acknowledgment messages, the body of the acknowledgment message is empty. You must refer to the original message to see the message body. For negative acknowledgment messages (with the exception of private, encrypted messages) the body of the acknowledgment message contains the message body of the original message.
PROPID_M_CLASS (Class)	Specifies the appropriate positive or negative acknowledgment class.
PROPID_M_CORRELATIONID (CorrelationId)	Specifies the original application message identifier (the PROPID_M_MSGID of the original message). If the correlation identifier of the original message contained an application-defined identifier, that information is not included in the acknowledgment message.
PROPID_M_DELIVERY (Delivery)	Same as original message.
PROPID_M_EXTENSION	Same as original message.
PROPID_M_JOURNAL (Journal)	Same as original message.
PROPID_M_LABEL (Label)	Same as original message.
PROPID_M_MSGID (id)	Message identifier for the acknowledgment message.
PROPID_M_PRIORITY (Priority)	Same as original message.
PROPID_M_RESP_QUEUE (ResponseQueueInfo)	Target queue of the original message.
PROPID_M_TIME_TO_BE_RECEIVED (MaxTimeToReceive)	Set to maximum time allowed by MSMQ.
PROPID_M_TIME_TO_REACH_QUEUE (MaxTimeToReachQueue)	Set to maximum time allowed by MSMQ.

Positive Acknowledgment Classes

MSMQ generates the following classes of positive acknowledgment messages:

MQMSG_CLASS_ACK_REACH_QUEUE. This class indicates the original message reached its destination queue.
MQMSG_CLASS_ACK_RECEIVE. This class indicates the original message was retrieved by the receiving application.

Negative Arrival Acknowledgment Classes

MSMQ generates the following classes of negative acknowledgment messages if the message fails to arrive at the queue:

MQMSG_CLASS_NACK_ACCESS_DENIED. This class indicates the sender does not have send access rights to the destination queue.
MQMSG_CLASS_NACK_BAD_DST_Q. This class indicates the destination queue is not available to the sender.
MQMSG_CLASS_NACK_BAD_ENCRYPTION. This class indicates the destination Queue manager could not decrypt a private message.
MQMSG_CLASS_NACK_BAD_SIGNATURE. This class indicates that MSMQ could not authenticate the original message. The original message's digital signature is not valid.
MQMSG_CLASS_NACK_COULD_NOT_ENCRYPT. This class indicates the source Queue manager could not encrypt a private message.
MQMSG_CLASS_NACK_HOP_COUNT_EXCEEDED. This class indicates the message hop count was exceeded. The maximum hop count is set by MSMQ (hop count = 15) and cannot be changed.
MQMSG_CLASS_NACK_Q_EXCEED_QUOTA. This class indicates the message was not delivered because the destination queue is full.
MQMSG_CLASS_NACK_REACH_QUEUE_TIMEOUT. This class indicates that the message did not reach the destination queue. It can be generated by either the time-to-reach-queue or time-to-be-received timer.
MQMSG_CLASS_NACK_PURGED. This class indicates the message was purged before reaching the destination queue.
MQMSG_CLASS_NACK_NOT_TRANSACTIONAL_Q. This class indicates a transaction message was sent to a non-transaction queue.
MQMSG_CLASS_NACK_NOT_TRANSACTIONAL_MSG. This class indicates a non-transaction message was sent to a transaction queue.

Negative Read Acknowledgment Classes

MSMQ generates the following classes of negative acknowledgment messages if the original message in the queue could not be read:

MQMSG_CLASS_NACK_Q_DELETED. This class indicates the queue was deleted before the message could be read from the queue.
MQMSG_CLASS_NACK_Q_PURGED. This class indicates that the queue was purged and the message no longer exists.
MQMSG_CLASS_NACK_RECEIVE_TIMEOUT. This class indicates that the message was not retrieved from the queue before its time-to-be-received timer expired.

For an example of returning acknowledgment messages, see:

Sending Messages that Request Acknowledgments (using API functions)
Sending Messages that Request Acknowledgments (using ActiveX components)