MSMQ provides two timers to help you maintain better control of your messages: a time-to-be-received and a time-to-reach-queue timer.
The time-to-be-received timer determines how long a message remains in the system, starting from the time the message is sent to the time it is removed from the target queue.
The time-to-reach-queue timer determines how long a message has until it reaches the target Queue Manager of the target queue. Typically, this timer is set to a value less than the time-to-be-received setting.
When both timers are used, if the time-to-be-received timer is set to a shorter time interval than the time-to-reach-queue timer, it takes precedence over the time-to-reach-queue timer. MSMQ does not allow messages to remain in the system longer than the time allowed by their time-to-be-received timer.
When either timer expires, MSMQ discards the message. However, MSMQ can also send a copy of the message to a dead letter queue or an acknowledgment message to an administration queue. If the message's acknowledgment property specifies full or negative acknowledgments, MSMQ sends the appropriate negative acknowledgment message to the administration queue specified by the message. If the message's journal property specifies a dead letter queue, a copy of the message is sent to one of two places. The copies of non-transactional messages are sent to the dead letter queue on the computer where the timer expired. Copies of transactional messages are copied to the transactional dead letter queue on the source machine.
For more information see: