Carriers that are sent a private load will be notified by email once a day.  Carriers do not need to have a DAT load board subscription to view private loads sent to them.  Just download the DAT One (Mobile) app located in the Google Play or Apple App store and sign up for a free account.  Private loads can be viewed directly from DAT One once you are signed up and signed in.  When signed in, the app will notify you each time a private load is received.