Managing email with LinuxConf on RedHat 6.0
by Dan Potter
1999.09.13.01

1. Sendmail Software Installation

   The installation of the email software itself should have occured during initial RedHat setup; the relevant RPM file is sendmail-8.9.3-10.

2. Preliminary setup in Linuxconf

   Email is handled in RedHat by the ubiquitous sendmail program. As with most other things in this course, we'll be configuring email the easy way, with Linuxconf.

   Two settings need to set in the basic email setup. Cursor down in Linuxconf to the heading Mail delivery system (sendmail), then go down to Basic and basic information. Press ENTER on that line. In the "Present your system as" field, enter the domain name your server is handling (for example, "company.com"). This information was decided earlier in the install and that information needs to match this information. The next line is a checkbox that says "Accept email for ...". Press SPACE on this line. TAB to "Accept" at the bottom of the screen and hit ENTER. A dialog box will pop up asking if you'd like to generate a new sendmail.cf; press ENTER to accept. Another dialog may appear asking if you'd like to general sendmail.cf for the first time; again press ENTER to accept. A notice will pop up confirming the action. You should now be back on the main Linuxconf screen.

3. Finding the accounts section in Linuxconf

   Even though there is an entire section for configuring email, most of the default settings in that section are just fine for most setups. Most of the dirty work will be done in the User Accounts section, located under Config. You'll need to cursor down a ways to see that section. Do that now.

4. Adding an email account

   To add an email account, you'll need to add an actual login to the system. This process will cause the server to receive email for that user, and to allow them to check their mail remotely with the common POP-3 protocol.

   1. Press ENTER on User Accounts under Normal.
   2. TAB to the "Add" button and press ENTER.
   3. Cursor down to "Login name" and enter a short user name for the user; this should generally be all lower case and contain only letters and numbers. This will also determine the email address of the user. If your machine is named www.company.com, and you create an account with the login "bob", then the address will be "bob@company.com".
   4. Cursor down to "Full name" and enter the user's human-readable name, such as "Bob Constantinopolis".
   5. If the user's mail is to be redirected elsewhere, then cursor down to "Redirect messages to" and enter an email address.
   6. TAB to the "Accept" button at the bottom of the screen and press ENTER.
   7. You will be prompted for a password for the user. This box will hold you to some standards about good password choices. This may be annoying, but it's not nearly as annoying as rebuilding your box at 4 in the morning when the mean people broke in. Once you enter a password, press ENTER; you will be asked for a confirmation to make sure it was typed correctly.
   8. You should now be back at the "User accounts" screen. Repeat the above procedure for as many accounts as you want, then TAB to "Quit" and press ENTER.
   9. TAB down to "Act/Changes" and press ENTER. Press ENTER on "Activate the changes" to activate the changes.

   The account should now be ready to go.

5. Turning forwarding on or off

   Later on you may want to enable or disable forwarding for a particular account. Here is the procedure; this assumes the same starting place as the above step.

   1. Press ENTER on User Accounts under Normal.
   2. Cursor down to the account you wish to edit, and press ENTER.
   3. Cursor down to "Redirect messages to". If you wish to disable forwarding, then remove the text in that field (using backspace). If you wish to enable forwarding or change the forwarding destination, enter an email address as appropriate.
   4. TAB to the "Accept" button at the bottom of the screen and press ENTER.
   5. You should now be back at the "User accounts" screen. Repeat the above procedure for as many accounts as you want, then TAB to "Quit" and press ENTER.
   6. TAB down to "Act/Changes" and press ENTER. Press ENTER on "Activate the changes" to activate the changes.

   The changes should be done.

6. Enabling and disable email accounts

   Later on you may want to enable or disable a particular account. Here is the procedure; this assumes the same starting place as the above steps.

   1. Press ENTER on User Accounts under Normal.
   2. Cursor down to the account you wish to edit, and press ENTER.
   3. If you wish to enable a disabled account, press SPACE until the box is checked. If you wish to disable an enabled account, press SPACE until the box is unchecked.
   4. TAB to the "Accept" button at the bottom of the screen and press ENTER.
   5. You should now be back at the "User accounts" screen. Repeat the above procedure for as many accounts as you want, then TAB to "Quit" and press ENTER.
   6. TAB down to "Act/Changes" and press ENTER. Press ENTER on "Activate the changes" to activate the changes.

   The changes should be done.

7. Testing the server

   To do a really quick check on your email accounts, use the following procedure from a shell prompt:

   • Type

     mail -s Testing bob@company.com

     Note: Please replace "bob@company.com" with the full email address of the account you wish to test.
   • Type a short message such as "this is a test." Once you're done, press ENTER to get on a blank link. Then type CTRL-D (press the Ctrl key and D), and ENTER. A prompt "Cc:" will come up. Just hit ENTER again.
   • Your message should be delivered now. To check that without having to use a mail client, type this:

     ls -l /var/spool/mail

     You should see an entry for the user you just added, by the login name. If you don't want them to receive your test message, then use this command:

     rm /var/spool/mail/user

     and then confirm the remove. Note: Replace "user" in the above with the user name, such as "bob". Note that this will not work for forwarded accounts, since the mail will have been bounced to that address already.

   If that worked, you should be ready to go!

8. Removing an account

   You may eventually need to remove an account as well. Unfortunately Linuxconf hasn't added that functionality yet. Free software is good but there aren't always enough people to work on the lesser used functions. Here is how to do it from the shell prompt:

   /usr/sbin/userdel -r username

   This will delete the user whose login name is username (this is the first part of their email address, before the @ sign).

9. Relevant information for further investigation

   Like other parts of this course, you may want to explore the inner workings of sendmail and user accounts more closely than we cover in class. Here are some relevant files and directories for editing the config directly. Please exercise caution when exploring these files, should you decide to do that.

   • /usr/doc/sendmail -- Documentation on sendmail
   • /etc/passwd -- List of the active users
   • /etc/shadow -- Lists user password secrets; viewable only by root
   • passwd -- Utility to change passwords manually
   • chfn -- Utility to change user account info manually
   • /etc/sendmail.cf -- The rather obtuse Sendmail config file
   • /etc/sendmail.cw -- The list of accept aliases for Sendmail