You can control whether any particular instance of Messaging Server makes its POP, IMAP, or HTTP service available for use. This is not the same as starting and stopping services (see 4.4 Starting and Stopping Services); to function, POP, IMAP, or HTTP must be both enabled and started.
Enabling a service is a more “global” process than starting or stopping a service. For example, the Enable setting persists across system reboots, whereas you must restart a previously “stopped” service after a reboot.
There is no need to enable services that you do not plan to use. For example, if a Messaging Server instance is used only as a mail transfer agent (MTA), you should disable POP, IMAP, and HTTP. If it is used only for POP services, you should disable IMAP and HTTP. If it used only for web-based email, you should disable both POP and IMAP.
You can enable or disable services at the server level. This process is described in this chapter. 220.127.116.11 To Specify What Services Can Be Started also describes this process. You can also enable or disable services at the user level by setting the LDAP attribute mailAllowedServiceAccess.