Retrieves metrics for the messages associated with a send definition, including messages that haven't been processed yet.
|Required. The unique identifier of the definition.
This example checks the queue depth and age of the oldest record that hasn't been processed. If you set a definition to inactive and continue to send message requests to it, the count and age increase.
If the request is successful, the response includes a unique ID for the request. It also includes the number of records that are waiting to be processed in the queue and the age of the oldest unprocessed record in the queue.