I've been given a 4.2.4 system to look into since the previous admin left some time ago.
I have found we are seeing the following
Error pn datax IncidentXmlNotificationServlet PN-1100: Java message: Error sending XML Notification. Incident Queue is full.
and we no longer get the previously configured XML emailed actions when a rule gets hit.
I have been looking trying to determine what and how needs to be cleared.
Any insight would be appreciated.