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Chapter 8

Chapter 8. Providing E-mail Services. Overview. Understand the e-mail environment Understand e-mail protocols Administering the Microsoft Exchange 2000 Installation and administering sendmail for Linux Install and configure IMAP4 and POP3 servers for Linux.

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Chapter 8

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  1. Chapter 8 Providing E-mail Services

  2. Overview • Understand the e-mail environment • Understand e-mail protocols • Administering the Microsoft Exchange 2000 • Installation and administering sendmail for Linux • Install and configure IMAP4 and POP3 servers for Linux

  3. Understanding the E-mail Environment • E-mail evolved from a variety of proprietary systems • In the 1980s and 1990s, people often had e-mail addresses on a number of systems • Even as late as 1997, many email servers were not able to take advantage of Internet e-mail • Most common email server products • Sendmail (Linux) • Exchange (Windows)

  4. Exchange 2000 Goes Beyond E-mail Basics • Instant messaging • Unified messaging platform • Single inbox for e-mail, voicemail, fax • Chat service • URL addressing • Use a single URL to access stored data • Audio and video conferencing • What about the goofy cartoons (emotions) you can include in your email?

  5. Role of DNS in E-mail Systems • Sending email messages requires configuring DNS • A domain name, such as technowidgets.com, needs to be associated with two IP addresses • One IP address can be for a Web site • Another IP address is for e-mail • To associate a domain name, or any other host name, with the IP address of an e-mail server, you need a mail exchange (MX) record technowidgets.com. IN MX 10 mail.technowidgets.com. • The 10 refers to the priority of the e-mail server if there are multiple e-mail servers • IN indicating the domain name • MX representing a Mail Exchange (MX) record – other options could be A or NS

  6. E-mail System Terminology • MTA (Mail Transfer Agent) • Accepts e-mail from clients and sends e-mail to another MTA for storage • Exchange 2000, sendmail • MUA (Mail User Agent) • E-mail client software • Formats the message and prepares it for sending to MTA • Outlook, KMail • MDA (Mail Delivery Agent) • Part of the email server • Delivers e-mail from server to MUA • Exchange 2000, imap-2001

  7. E-mail System Terminology • Masquerading • Replace actual host name with domain name • Actual host name is replaced • mail2.technowidgets.com  ffarid@ mail2.technowidgets.com becomes ffarid@ technowidgets.com (masking the full host name) • Relaying • The process of sending e-mail to an intermediate e-mail server (MTA) before the message is transmitted to its final destination • When single MTA is available, relaying should not be allowed from the Internet because spammers could use it to send e-mail

  8. E-mail Protocols • SMTP (Simple Mail Transfer Protocol) • Text-based protocol used to send e-mail messages • Does not concern any concerns about security • Both client and server use it • POP3 (Post Office Protocol) • To retrieve e-mail • Email client uses it to read, list, and delete email messages • Typically, all messages are downloaded to a client • IMAP4 (Internet Mail Access Protocol) • More complex than POP3 • To retrieve e-mail • E-mail stays on the server and can be retrieved from any computer that has an email client and supports the protocol • You can create folders on server to store e-mail

  9. Understanding SMTP • The commands are processed by the SMTP server

  10. Understanding SMTP • The SMTP headers add descriptive information

  11. Understanding SMTP • Sample session (commands and headers) HELO WKS1 Sending the name of the host 250 web1.technowidgets.com Hello [127.0.0.1] MAIL FROM: XYZ@yahoo.com 250 2.1.0 xyz@yahoo.com....Sender OK RCPT TO: cbranco@technowidgets.com 250 2.1.5 cbranco@technowidgets.com DATA 354 Start mail input; end with <CRLF>.<CRLF> This is a simple message . QUIT Response Code Carriage Return Line feed

  12. Understanding POP3 • Less complex than IMAP4 • First step is to logon with user name and password • List, read, download, delete e-mail

  13. Common POP3 commands

  14. Understanding IMAP4 • Messages remain on server • Requires much more space on server • To keep track of the status of messages, flags are used (For example your free yahoo account) • \Recent • \Seen • \Answered • \Flagged • \Deleted • \Draft

  15. Common IMAP4 commands

  16. Installing Microsoft Exchange 2000 • Install SMTP is part of IIS Web Server • Install NNTP (Network News Transport Protocol), also a part of IIS • Used for newsgroup • Active Directory is required for Exchange • Once the above are installed, the Exchange wizard guides you through a simple installation • Then, to use Exchange 2000 on Windows Server 2003, install Exchange 2000 Service Pack 3 is required

  17. Installing and Configuring Sendmail for Linux • Installed sendmail • includes SMTP only • Configure sendmail through a macro called m4 • m4 /etc/mail/sendmail.mc >/etc/mail/sendmail.cf • The macro is processed and sendmail.cf is created • There are many advanced features of sendmail that make configuring it substantially difficult • There are other e-mail servers, such as qmail, that are easier

  18. Minimal sendmail.mc File divert(-1) include(`/usr/share/sendmail-cf/m4/cf.m4') OSTYPE(`linux') define(`PROCMAIL_MAILER_PATH',`/usr/bin/procmail')dnl FEATURE(local_procmail,`',`procmail -t -Y -a $h -d $u')dnl MAILER(smtp)dnl MAILER(procmail)dnl Cwtechnowidgets.com Notice that the strings are enclosed with a backtick and an apostrophe as in `linux'

  19. Configuring E-mail Clients-Typical Information Required • SMTP server IP address • Your e-mail address • Your e-mail password • POP3 or IMAP4 server IP address

  20. Summary • E-mail has evolved over the years • Microsoft Exchange 2000 and sendmail are the two of the most popular e-mail server products • DNS plays a central role in messaging • Three major protocols are involved in e-mail • SMTP, POP3, and IMAP4

  21. Projects and Labs

  22. Linux Projects • Project 8-1 • Make sure your DNS works • Go to page 374-375 and make sure you have added the two email entries in your reverse lookup table • Make sure sendmail is installed: You should have checked the mail server box • If you have to install it, there is no need to Start the program • You should have a /etc/mail/sendmail.mc file. Make a back up of this file and modify it according to the text page 424 • Using m4 utility create sendmail.cf page 424 step 5 • Create a telnet session to send email • telnet localhost 25 send a message to zzz@yyy.com • Do cat /var/spool/mail/ zzz@yyy.com  you should see the message • Project 8-2 • Test IMAP4/POP3 • telnet localhost 143  Results must be similar to Page 428 • telnet localhost 110  Results must be similar to Page 429 • Project 8-5 • Configure Kmail in Linux – create two users and send emails to each other • Project 8-7 • Do cat /var/spool/mail  display all the messages (header and contents) the user has received • Two servers should be able to send email messages to each other!

  23. Windows Lab • Do project 8-9 page 437 • Send email from a Linux server to a Windows machine. If you Install Exchange 2000, and do you will receive Extra credit! Page 389- Installation steps! Page 392-Adminstering Project 8-3 page 429

  24. Homework (April. 5rd) - submit through WebCT • How can you access your email by using a browser in Linux? (Read chapter 8 pages 417-419; in Windows Web-based email product is OWA (Outlook Web Access). OWA uses XML or Dynamic HTML to transfer format processing from the server to the browser). Is there a similar capability in Linux? Is there a software to support Webmail for Linux? Are there software products that allow transferring format processing from the server to the browser? ) • Extra Credit - Write a step-by-step procedure to install a software product in Linux that allows webmail. • What is qmail in Linux? Can we use it instead of sendmail? What is it used for? • Extra Credit – Implement qmail on a server in the lab or write a step-by-step procedure. (Do not copy the procedure from the Web – I have already read that! To get extra credit, you should write your own SHORT version) • Find a Linux-based package that can be configured to allow instant messaging, (or audio and video conferencing). What is the difference between Gaim and Kopete? • What is multicasting? What is source tree multicasting? Does email server utilizes multicasting? How? • One way spammers send unsolicited email is by masquerading their message such that they appear to have come from your organization or some safe source. Elaborate on such spamming techniques. What do they do so that you cannot detect them? (Read about spamming technique. There are lots of ways to send spam and not get detected – There are many interesting articles about this in PCWORLD.com – Don’t just copy and paste – I have read them! Just write a brief summary) • Let me know if you find errors in the book! Maximum Extra Credit will be 20 points

  25. Errors in the book

  26. Linux Email Server Labs • Install sendmail (page 400 step 1-9) • Configure the sendmail as sendmail.mc and store it in >/etc/mail/ • Install and configure IMP4 and POP3 (page 404) • Configure email client in Linux: Kmail  installed automatically – create an account • If you have problem with Kmail you may need to reinstall Kmail

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