In Event Viewer, both the application log and the system log contain errors, warnings, and informational events that are related to the operation of Exchange Server, the SMTP service, and other applications. To identify the cause of message flow issues, carefully review the data that is contained in the application log and system log.
Use the following procedure to view errors, warnings, and informational events in the system log for the SMTP service.
To view the system log in Event Viewer
Click Start, point to Programs, point to Administrative Tools, and then click Event Viewer.
In the console tree, click System Log.
To sort the log alphabetically and quickly locate an entry for an Exchange service, in the details pane, click Source.
Double-click a log entry to open an event's properties page.
To filter the log to list entries for a specific type of SMTP service events, from the View menu, click Filter.
In System Log Properties, in the Event source list, select SMTPSVC.
In the Category list, select a specific set of events or, to view all events for the SMTP service, leave the default setting at All.