Microsoft Exchange 2000 Server is a verbose product in terms of the amount of data that it writes into the event logs—the Application log in particular—especially when you've enabled diagnostics logging above the minimal level. The Application log's default size is 512KB, which is too small for any reasonably sized Exchange Server system. At this size, the log can fill too rapidly and overflow, obscuring important events. To avoid this possibility, consider increasing the Application log to 4MB (on servers that accommodate as many as 500 mailboxes) or larger (on servers that host more than 500 mailboxes). To change the size of an event log, edit the log's Properties dialog box.