Configuring Sendmail on IRIX 6.5.27 Systems

Sendmail on IRIX 6.5.27 is a major change from earlier versions. SGI's installation process uses sendmail version 8.12.11. There are many significant improvements over sendmail 8.9.3, the one previously used on Boston University SGI's. A full description of the available features can be found online at the Sendmail Web Site or the O'Reilly Sendmail book The change is so large that the old sendmail configuration files can no longer be used.

The standard BU installation uses a very simple default configuration, one that accepts mail only from people actually logged on, and sending it out through the main campus server, BU.EDU. It will not listen on the Internet for mail deliveries, so your computer cannot be highjacked by spammers to send their millions of messages throughout the World. Upgrading to IRIX 6.5.27 creates a "simpleclient" sendmail system.

Several alternatives are provided for those needing a more elaborate configuration. This document will explain how to choose one and configure it.

The most noticeable differences are:

• The sendmail daemon runs as user "sgismmsp", not "root". User "sgismmsp" belongs to group "sgismmsp", and several of the files and directories are accessible only to users and programs belong to this group. The BU installation scripts check that this user and group exist, creating them if necessary. The permissions of the relevant files and directories are also checked, and adjusted if necessary.
• Configuration files are located in a new directory, "/etc/mail", instead of "/etc". Because SGI is still "transitioning" to this new directory structure, the three critical files "sendmail.cf", "sendmail.mc", and "aliases" are actually installed in "/etc", with symbolic links to them placed in "/etc/mail". Therefore, programs that look for them in "/etc/mail" will find them. The other configuration files are actually located in "/etc/mail".
• The actual Mail configuration is specified in a file called "sendmail.mc", and the command "configmail mc2cf" generates the actual ".cf" file. Instructions on making changes is contained in the "sendmail.mc" file itself. The ".mc" file is a greatly simplified ".cf" file, designed to be easily and clearly modified.

Two pre-configured ".mc" files are provided as part of the standard installation.

• A copy of "simpleclient.mc" is installed by default. it will deliver mail from people actually logged into the machine. It will immediately transfer the messages to "bu.edu" for processing and actual delivery. Mail messages will appear to come from "user@bu.edu". It doesn't accept mail from other computers, and so cannot be used by spammers to relay mail to the rest of the world. The mail server can be changed from "bu.edu" to another computer by editing the entry described in the file's comment section.
• If you need a "mail server", copy "workstation.mc" to sendmail.mc. "workstation.mc" is very similar to the standard SGI mail configuration. Mail messages will appear to come from this computer, and it will accept mail from the Internet addressed to users on this computer. It will not accept mail for other computers unless they are explicitly listed in the file "/etc/mail/sendmail.cw". Again, this is to prevent the inadvertent relaying of spam. Incorrect modification of this file can break these controls, so system administrators are encouraged to carefully test their computer carefully after making changes
• Type configmail mc2cf to generate the actual "sendmail.cf" file.
• If the machine is a "mail server", type checkconfig sendmail on to make sure mail is started after a reboot.
Contact sgihelp@bu.edu for assistance if necessary.