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Sun Java System Messaging Server 6.3 Administration Guide

5.1 General Configuration

Configuring the general features of the Messaging Server POP, IMAP, and HTTP services includes enabling or disabling the services, assigning port numbers, and optionally modifying service banners sent to connecting clients. This section provides background information; for the steps you follow to make these settings, see 5.5 To Configure POP Services, 5.6 To Configure IMAP Services and 5.7 To Configure HTTP Services. This section consists of the following subsections:

5.1.1 Enabling and Disabling Services

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. 4.4.2.1 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.

5.1.2 Specifying Port Numbers

For each service, you can specify the port number that the server is to use for service connections:

You might need to specify a port number other than the default if you have, for example, two or more IMAP server instances on a single host machine, or if you are using the same host machine as both an IMAP server and a Messaging Multiplexor server. (For information about the Multiplexor, see Chapter 7, Configuring and Administering Multiplexor Services.

Keep the following in mind when you specify a port:

5.1.3 Ports for Encrypted Communications

Messaging Server supports encrypted communications with IMAP, POP and HTTP clients by using the Secure Sockets Layer (SSL) protocol. For general information on support for SSL in Messaging Server, see 23.5 Configuring Encryption and Certificate-Based Authentication.

5.1.3.1 IMAP Over SSL

You can accept the default (recommended) IMAP over SSL port number (993) or you can specify a different port for IMAP over SSL.

Messaging Server provides the option of using separate ports for IMAP and IMAP over SSL because most current IMAP clients require separate ports for them. Same-port communication with both IMAP and IMAP over SSL is an emerging standard; as long as your Messaging Server has an installed SSL certificate (see 23.5.1 Obtaining Certificates), it can support same-port IMAP over SSL.

5.1.3.2 POP Over SSL

The default separate SSL port for POP is 995. One can also initiate SSL over normal POP port with the command “STLS” (see 5.5 To Configure POP Services).

5.1.3.3 HTTP Over SSL

You can accept the default HTTP over SSL port number (443) or you can specify a different port for HTTPS.

5.1.4 Service Banner

When a client first connects to the Messaging Server POP or IMAP port, the server sends an identifying text string to the client. This service banner (not normally displayed to the client’s user) identifies the server as Sun Java System Messaging Server, and gives the server’s version number. The banner is most typically used for client debugging or problem-isolation purposes.

You can replace the default banner for the POP or IMAP service if you want a different message sent to connecting clients.

Use the configutil utility (service.imap.banner, service.pop.banner) to set service banners. For detailed syntax information about configutil, see the Sun Java System Messaging Server 6.3 Administration Reference.