As per Microsoft: "Ensure that the latest service packs have been applied to the Exchange server. Also, check to see if any third-party products that are related to Exchange or Outlook have been installed. If so, try to uninstall those products and see if this eliminates the problem". See MSEX2K3DB for more details.
Build a great reporting interface using Splunk, one of the leaders in the Security Information and Event Management (SIEM) field, linking the collected Windows events to www.eventid.net.
Obtain enhanced visibility into Cisco ASA firewall logs using the free Firegen for Cisco ASA Splunk App. Take advantage of dashboards built to optimize the threat analysis process.