When a message is retrieved from the queue using PeekMessage, the message is not dequeued and the visibility of the message remains unchanged. The message remains available to other clients until a client retrieves the message with a call to GetMessage. The call to PeekMessage does not update the message's PopReceipt value, so the message cannot subsequently be deleted. Additionally, calling PeekMessage does not update the message's NextVisibleTime or DequeueCount properties.
Only messages that are visible may be retrieved with PeekMessage.