1. Providing E-mail Services
Chapter 8
Providing 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
evolved from a variety of proprietary systems
In the 1980s and 1990s, people often had addresses on a number of systems
Even as late as 1997, many servers were not able to take advantage of Internet
Most common server products
Sendmail (Linux)
Exchange (Windows)

4. Exchange 2000 Goes Beyond E-mail Basics
Instant messaging
Unified messaging platform
Single inbox for , voic , 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 ?

5. Role of DNS in E-mail Systems
Sending 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
To associate a domain name, or any other host name, with the IP address of an server, you need a mail exchange (MX) record
technowidgets.com. IN MX 10 mail.technowidgets.com.
The 10 refers to the priority of the server if there are multiple 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 from clients and sends to another MTA for storage
Exchange 2000, sendmail
MUA (Mail User Agent)
client software
Formats the message and prepares it for sending to MTA
Outlook, KMail
MDA (Mail Delivery Agent)
Part of the server
Delivers 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  mail2.technowidgets.com becomes technowidgets.com (masking the full host name)
Relaying
The process of sending to an intermediate 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

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

9. Understanding SMTP The commands are processed by the SMTP server
Purpose
HELO
Identifies the domain sending the message
DATA
Indicates the body of the message
VRFY
Verifies the user
QUIT
Ends the SMTP session

10. Understanding SMTP The SMTP headers add descriptive information Header
Description
MAIL FROM:
Identifies who is sending the message (required)
RCPT TO:
Identifies the recipient of the message (required)
RECEIVED:
Identifies the server that processed the message
DATE:
Indicates the date of the
FROM:
Shows the address as it is typically displayed in an client
SUBJECT:
Shows the subject of the message
TO:
Shows the recipient as it is typically displayed in an client
CC:
Sends copies of the message to a list of addresses
BCC:
Sends copies of the message to a list of addresses but does not display the addresses

11. Understanding SMTP Sample session (commands and headers)
HELO WKS1  Sending the name of the host
250 web1.technowidgets.com Hello [ ]
MAIL FROM: OK
RCPT TO:
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

13. Common POP3 commands Command Description USER username
Connects to POP3 server based on user name
PASS password
Enters the password for the user, as in PASS: Ax6yy
LIST
Displays the message number followed by the number of
characters in the message
UIDL
Displays the unique ID for each message
RETR n
Replaces the n with a message number to retrieve that message
TOP n lines
Instead of retrieving the whole message, retrieves the number of
lines designated by the lines parameter for message number n
DELE n
Deletes message number n from the server
QUIT
Ends the session

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 Command Description LOGIN username password
Log on to the server with your user name and password, which are unencrypted.
SELECT mailbox
Select a mailbox before you perform mail tasks. The default mailbox is called inbox. The response gives a summary of mailbox information.
FETCH message(s) item(s)
Retrieve messages. The message(s) parameter gives the message number. The item(s) parameter determines what part of the message is fetched—that is, individual header items or the body of the text.
STORE message(s) flags
Change the flags associated with a message. Typically, this command is used to mark messages to be deleted, undeleted, or identified as unread.
LOGOUT
End the IMAP4 session.

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 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 address
Your 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 server products
DNS plays a central role in messaging
Three major protocols are involved in
SMTP, POP3, and IMAP4

21. Projects and Labs

22. Linux Projects Project 8-1 Project 8-2 Project 8-5 Project 8-7
Make sure your DNS works
Go to page and make sure you have added the two 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
telnet localhost 25  send a message to
Do cat /var/spool/mail/  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 s 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 messages to each other!

23. Windows Lab Do project 8-9 page 437
Send 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 by using a browser in Linux? (Read chapter 8 pages ; in Windows Web-based 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 server utilizes multicasting? How?
One way spammers send unsolicited 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 client in Linux: Kmail  installed automatically – create an account
If you have problem with Kmail you may need to reinstall Kmail