Lesson 12

This module discussed how procmail is a email manipulation tool for Red Hat Linux. Administrators and users both can benefit from its power and flexibility. Red Hat Linux makes using procmail simple, so there's no reason not to take advantage of it. In this module, you learned about procmail's purpose and configuration. You saw how the procmail program uses recipes to identify and take action on email. You learned that procmail can identify and continue processing email, save the email to a folder, forward the email to a program, or forward the email to another email address. Finally, you learned email filtering techniques and how to troubleshoot procmail.

Having completed this module, you should now be able to:

1. Describe procmail and its use
2. Configure procmail
3. Compare condition and action flags
4. Identify recipe conditions
5. Describe recipe actions
6. Invoke procmail
7. List techniques for filtering mail
8. Test procmail filters
9. Troubleshoot procmail

This module introduced you to the following terms:

1. Action flag: A flag that modifies the behavior of a procmail recipe's action.
2. Action line: A line in a procmail recipe that specifies the recipe's action.
3. Bit bucket: UNIX jargon for /dev/null. It is a device that data can be written into, but never retrieved from. In effect, it is an information trashcan.
4. Bounce: To resend an email to another recipient, but retain the original email envelope. This makes an email you bounce to someone look as though he or she received it from the original sender.
5. Condition: The regular expressions in a procmail recipe.
6. Condition flags: Flags that modify a procmail recipe's condition.
7. Delivering recipes','Recipes that save the email to a folder.
8. Delivery headers: Routing and control information found at the beginning of every email. Common headers include the destination (the "To:" header), the sender (the "From:" header), and the subject (the "Subj:" header).
9. File lock: 'A flag the operating system sets to prevent multiple programs from updating the same file simultaneously.
10. Inbox: A user's primary email mailbox, into which all unfiltered mail flows.
11. Mail Delivery Agents (MDA)': The email agents responsible for local network email delivery.
12. Mail User Agents (MUA): Programs responsible for displaying and composing email.
13. Metacharacter: A character that has a special meaning to a regular expression.
14. Non-delivering recipes: Recipes that do not save email to a folder, but perform some other action (such as sending the email to an external program) on the email.
15. Recipes: 'A concise set of procmail instructions that filter or otherwise manipulate an email.
16. Regular expressions: A string expression that uses special metacharacters (wildcards, for example) to match zero or more strings. Regular expressions are the foundation for many Linux programs, including the UNIX command line file-matching routines (e.g., "ls myfile.*"), grep (e.g., "grep bar foo.txt"), and procmail.
17. SPAM: A common name for unsolicited email, named after a Monty Python sketch.
18. Vacuously: A statement applies vacuously when it is obviously true in all contexts.
19. Variable definitions: Assigning a value to a variable.

The next module discusses how to control host access with TCP wrappers.

Before you move to the next module, click the Quiz link below to test your understanding of procmail configuration.
Procmail Concepts - Quiz