sendmail Configuration File

A configuration file controls the way that sendmail performs its functions. The configuration file determines the choice of delivery agents, address rewriting rules, and the format of the mail header.

The sendmail program uses the information from the /etc/mail/sendmail.cf file to perform its functions. Each system has a default sendmail.cf file that is installed in the /etc/mail directory. You do not need to edit or change the default configuration file for mail servers or mail clients. The only systems that require a customized configuration file are mail hosts and mail gateways.

The Solaris operating environment provides three default configuration files in the /etc/mail directory.

1. A configuration file that is named main.cf for the system (or systems) you designate as the mail host or a mail gateway

2. A configuration file that is named subsidiary.cf, which is a duplicate copy of the default sendmail.cf file

3. A configuration file that is named submit.cf, which is used to run sendmail in mail submission program mode, instead of daemon mode. For more information, refer to New Configuration File, submit.cf.

The configuration file you use on a system depends on the role of the system in your mail service.

• For mail clients or mail servers, you do not need to do anything to set up or edit the default configuration file.

• To set up a mail host or mail gateway, copy the main.cf file and rename it to sendmail.cf in the /etc/mail directory. Then reconfigure the sendmail configuration file to set the relay mailer and relay host parameters that are needed for your mail configuration. For task information, refer to Setting Up Mail Services (Task Map) or Building the sendmail.cf Configuration File (Task) in Chapter 25, Mail Services (Tasks).

The following list describes some configuration parameters you can change, depending on the requirements of your site.

• Time values, which specify the following information.

  • Read timeouts. Refer to Changes to the Timeout Option.

  • Length of time a message remains undelivered in the queue before it is returned to the sender. Refer to New Queue Features. For a task map, refer to Administering the Queue Directories (Task Map).

• Delivery modes, which specify how quickly mail is delivered.

• Load limits, which increase efficiency during busy periods by not attempting to deliver large messages, messages to many recipients, and messages to sites that have been down for a long time.

• Log level, which specifies the kinds of problems that are logged.