Web server administration chap08

 Install and configure IMAP4 and POP3 servers for Linux  Configure e-mail clients  Understand Web-based e-mail clients... E-mail System Terminology MTA Mail Transfer Agent  Accept

Web Server Administration

Chapter 8 Providing E-mail Services

 Understand the e-mail

environment

 Understand e-mail protocols

 Install and administer Microsoft

Exchange 2000

 Install and administer sendmail for Linux

 Install and configure IMAP4 and

POP3 servers for Linux

 Configure e-mail clients

 Understand Web-based e-mail

clients

Understanding the E-mail Environment

 E-mail evolved from a variety of

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

Role of DNS in E-mail

Systems

 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 an 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

E-mail System Terminology

 MTA (Mail Transfer Agent)

 Accepts mail from clients and sends

e-mail to another MTA for storage

 Exchange 2000, sendmail

 MUA (Mail User Agent)

 E-mail client

 Outlook, KMail

 MDA (Mail Delivery Agent)

 Delivers e-mail from server to MUA

 Exchange 2000, imap-2001

E-mail System Terminology

 Masquerading

 Replace actual host name with domain name

 Relaying

 The process of sending e-mail to an

intermediate e-mail server before the message

is transmitted to its final destination

 This should not be allowed from the Internet because spammers could use it to send e-mail

 Spammer

 Someone who sends unsolicited e-mail,

typically to try to sell something

E-mail Protocols

 SMTP (Simple Mail Transfer Protocol)

 To send e-mail messages

 POP3 (Post Office Protocol)

 E-mail stays on the server

 You can create folders on server to store e-mail

Understanding SMTP

 The commands are processed by

the SMTP server

Command Purpose

HELO Identifies the domain sending the message

DATA Indicates the body of the message

VRFY Verifies the e-mail user

QUIT Ends the SMTP session

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 e-mail server that processed the message

DATE: Indicates the date of the e-mail

FROM: Shows the e-mail address as it is typically displayed in an e-mail client

SUBJECT: Shows the subject of the e-mail message

TO: Shows the recipient as it is typically displayed in an e-mail client

CC: Sends copies of the message to a list of e-mail addresses

354 Start mail input; end with <CRLF>.<CRLF>

This is a simple message

.

QUIT

Understanding POP3

 More simplistic than IMAP4

 First step is to log on with user

name and password

 List, read, download, delete e-mail

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

Sample POP3

Understanding IMAP4

 Messages remain on server

 Requires much more space on server

 To keep track of the status of messages, flags are used

Common IMAP4 commands

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

and is also part of IIS

 Active Directory is required for Exchange

 Once the above are installed, the

Exchange wizard guides you through a simple installation

 To use Exchange 2000 on Windows

Server 2003, Exchange 2000 Service

Pack 3 is required

Administering Exchange Users

 When you add a

user, you have

the option to

create a mailbox

 By default, the

e-mail name is the

same as the user

name but you

can change it

Exchange 2000 Delivery Restrictions

 You can restrict

the size of

messages being

sent and received

 The e-mail names

of senders can be

restricted too

Installing and Configuring Sendmail for Linux

 Installed from an rpm file

 Configure sendmail through a

macro processor called m4

 m4 /etc/mail/sendmail.mc >/etc/mail/sendmail.cf

 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

Minimal sendmail.mc File

Notice that the strings are enclosed with a backtick

and an apostrophe as in `linux'

Installing and Configuring IMAP4 and POP3 for Linux

 Both IMAP4 and POP3 are included in

the imap-2001 package

 Once installed, you have to enable the daemons by either editing their

configuration files such as

/etc/xinetd.d/imap or using chkconfig

Configuring E-mail Typical Information

Clients-Required

 SMTP server IP address

 Your e-mail address

 Your e-mail password

 POP3 or IMAP4 server IP address

Web-based E-mail Clients

 Web-based e-mail clients allow you

to use your browser

 Exchange 2000 can be configured for Web-based e-mail using

Outlook Web Access

 Public sites, such as Microsoft's

Hotmail and Yahoo! Mail, have

been very popular

Web-based E-mail Advantages

Clients- Because a browser is used, no client configuration is needed

 The lack of configuration can significantly reduce

support costs

 No specialized client software is needed

 Users are not required to retrieve e-mail from

specific computers that have been configured for

them

 POP3 or IMAP4 protocols are not required, which

reduces server-side support

 Because Web-based e-mail is not constrained by

POP3 or IMAP4 protocols, a richer environment can

be developed that extends beyond basic e-mail

sendmail are the two of the most

popular e-mail server products

e-mail

 SMTP, POP3, and IMAP4