One of our spam servers had an issue overnight. It did not thrown any alarms because the service was “partially” running.  We noticed more spam than usual making it through the system this morning, so we did some checking.  After reviewing the message headers, we determined that the spam getting through was not actually being checked by the system.  Upon further investigation, we found a server malfunctioning.  The issue has been resolved now, so your spam levels should return to normal.