Check the log files to make sure the message store processes are running as configured. Messaging Server creates a separate set of log files for each of the major protocols, or services, it supports: SMTP, IMAP, POP, and HTTP. You can look at the log files in the directory msg-svr-base/log/. You should monitor the log files on a routine basis.
Be aware that logging can impact server performance. The more verbose the logging you specify, the more disk space your log files will occupy for a given amount of time. You should define effective but realistic log rotation, expiration, and backup policies for your server. For information about defining logging policies for your server, see Chapter 25, Managing Logging.