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Lesson 10

Unix sendmail Program (Conclusion)

In this module, you learned the basics of configuring, testing, and running the sendmail program. Now that you have completed this module, you should be able to:
  1. Explain the email process and the use of agents
  2. List the major responsibilities of the sendmail agent
  3. Describe how sendmail uses the SMTP protocol to forward email across the Internet
  4. Compile sendmail
  5. Use a .mc template file and M4 to create a sendmail configuration file automatically
  6. Test a new sendmail configuration before deploying it
  7. Use nslookup to view MX records

Describe the Unix sendmail Program

Sendmail is a mail transfer agent (MTA) that is used to send and receive email messages on Unix-like operating systems. It was one of the first MTAs to be developed and has been widely used for many years. Sendmail operates as a daemon, listening for incoming connections and processing messages as they are received. It can be configured to work with various types of mail servers and can handle a wide range of email protocols, including Simple Mail Transfer Protocol (SMTP), Post Office Protocol (POP), and Internet Message Access Protocol (IMAP).
Sendmail is a powerful and flexible program, but it can be difficult to configure and maintain, particularly for inexperienced users. It is not as user-friendly as some of the more modern MTAs that have been developed in recent years. Despite this, Sendmail is still widely used on many Unix-like systems, particularly on servers where it is important to have a robust and reliable MTA.

Key terms

In this module, we used the following terms:
  1. aliasing: Aliasing allows all users to refer to users by simple nicknames or by names other than their UNIX user name
  2. M4: M4 is a macro language that works with sendmail and, among other things, greatly simplifies sendmail configuration.
  3. Mail Delivery Agent: A Mail Delivery Agent (MDA) copies the message from the Mail Transfer Agent (MTA) into the users mailbox file.
  4. Mail Exchange (MX) record: An MX record is a type of Resource Record that defines a mail exchange host.
  5. Mail Transfer Agent: A Mail Transfer Agent (MTA) is a program that routes email among different machines.
  6. Mail User Agent: A Mail User Agent (MUA) is a program that allows users to compose, send, receive, and access email messages
  7. masquerading: Masquerading is the ability for a sendmail daemon to rewrite a subdomain\'s email address.
  8. SMTP: Simple Mail Transport Protocol (SMTP) is an application layer protocol for routing email.

Using Configuring Sendmail - Quiz

Click the Quiz link below to take a multiple-choice quiz covering what you've learned in this module.
Using Configuring Sendmail - Quiz