Specifies the name of the queue to which message should be moved if it cannot be processed successfully.
Applicable only for a message that is being enqueued.
Possible values are:
A String containing a valid queue name
Null (Default)
A message is moved to the exception queue if the number of dequeue attempts has expired or has exceeded max_retries specified in the DBMS_AQADM.CREATE_QUEUE command.