By default, the maximum number of active connections from IMAP4 clients that the Sun Message Store accepts is 10,000. The Advanced Option section in the Sun Message Store property book enables you to expand the maximum number of connections using the maximum connections permitted option. The up and down arrows for this option allow you to select a value in the range of 50 to 2,000,000,000 (billion).
When raising the maximum number of connections, keep in mind that the Sun Message Store daemons reserve shared memory for interprocess communication based on this number. If too high of a number is configured, the Sun Message Store fails to allocate sufficient shared memory to handle the maximum number of connections specified. The Sun Message Store will log an error message and exit.
If you attempt to configure the mail server to accept above the maximum number of connections permitted, imaccessd will log a message stating that the maximum connection number was exceeded and that the default number of 10,000 is being enforced.