The University of Akron Summit College Business Technology Dept.

1. The University of AkronSummit CollegeBusiness Technology Dept. 2440: 141Web Site Administration Email Services Instructor: Enoch E. Damson

2. 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 • The standard for current e-mail services is to use DNS with a special Mail Exchange record • The Mail Exchange record contains the IP address of the mail server for a domain • To allow users to send images, video, audio, and other binary files via e-mails, the Multipurpose Internet Mail Extension (MIME) specification was developed Email Services

3. The E-mail Environment… • Email systems use three standard protocols to communicate: • For sending mail: • Simple Mail Transfer Protocol (SMTP) • For retrieving email from electronic mailboxes • Post Office Protocol (POP) • Internet Mail Access Protocol (IMAP) • Common e-mail packages (servers) include: • Sendmail, Postfix (Linux) • Microsoft Exchange (Windows) Email Services

4. Role of DNS in E-mail Systems • A domain name, such as example.org, 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 Email Services

5. Mail Services • Mail service has three distinct components: • Mail User Agent (MUA) – the mail client the user interacts with • E.g. Kmail, Alphine, Elm (Windows, Linux) • Mail Transfer Agent (MTA) – handles the process of getting mail from one site to another • E.g. Sendmail, Postfix (Linux) • Microsoft Exchange (Windows) • Mail Delivery Agent (MDA) – takes the message and gets it to the appropriate user mailbox, when received at the site • E.g. Procmail, Microsoft Exchange Email Services

6. 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 Email Services

7. Simple Mail Transfter Protocol (SMTP) • The main standard for mail transport across the Internet • Defines the method of sending mail from a host to another • Its major strengths include its: • Simplicity • Platform-independent • Requires that a host be capable of sending ASCII text to another host • Typically done using port 25 (SMTP) on a mail server • E.g. telnet mailserver 25 Email Services

8. Common SMTP Commands • Some major SMTP commands include: • HELO – used by clients to introduce themselves to the server (originating hostname) • E.g. HELO example.org • VRFY– verifies the email user • DATA – specifies the body of the message • QUIT – ends the SMTP session Email Services

9. Common SMTP Headers • Major SMTP headers include: • MAIL FROM: – informs the mail server about the email’s origin (sender’s email address) • E.g. MAIL FROM: someone@example.org • RCPT TO: – specifies the receiver’s email address • E.g. RCPT TO: customer@example.org • RECEIVED: – identifies the email server that processed the message • DATE: – indicates the date of the email • SUBJECT: – shows the subject of the email message • TO: – shows the recipient of the email message • CC: – sends copies of the message to a list of email addresses Email Services

10. Sample SMTP Session HELO WKS1 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 Email Services

11. Installing a Postfix Server in Linux • Install Postfix via RPM in Fedora: • yum –y install postfix • Download the Postfix source code from www.postfix.org • Use the tar command to unpack the contents: • tar xvzf postfix-2.5.1.tar.gz • Change into the postfix-2.5.1 directory and run the make command: • cd postfix-2.5.1 • make • Install the actual software • make install Email Services

12. Starting the Postfix Server in Linux • Disable Sendmail and enable Postfix, since Sendmail is the default mailer installed on Fedora and Red Hat Enterprise Linux (RHEL) distros: • chkconfigsendmail off • chkconfig postfix on • Start the Postfix process: • service sendmail stop • service postfix start Email Services

13. Configuring the Postfix Server • Configuring the Postfix server is done with the /etc/postfix/main.cf configuration file • The process configuration file for Postfix is the master.cf file • Used to change how to run Postfix processes Email Services

14. Details of the main.cf File • Some of the options in the main.cf file include: • myhostname • mydomain • myorigin • mydestination • mail_spool_directory • mynetworks • smtpd_banner • inet_protocol Email Services

15. Checking the Configuration in Linux • To check the current Postfix configuration, use: • postfix check Email Services

16. Running the Server in Linux • Starting the Postfix mail server is done by passing the start option to the postfix run control script: • /etc/init.d/postfix start • To reload Postfix after changes to the configuration files, use: • /etc/init.d/postfix reload • To check the mail queue on your system in case it is filled up: • mailq • To flush the mail queue: • postfix flush Email Services

17. Installing and Administering Microsoft Exchange • The Microsoft Exchange Server can be much more than a simple e-mail server • It supports: • SMTP, POP, and IMAP protocols • Also supports the Lightweight Directory Access Protocol (LDAP) • Collaboration in the form of chat services and instant messaging • Interaction with other e-mail servers such as Lotus Notes, Novell Groupwise, etc Email Services

18. Microsoft Exchange Features • The Microsoft Exchange Server also has the following features: • Unified messaging platform services • Supports Voice Profile for Internet Mail (VPIM) – for interoperability between voicemail systems • Conferencing services • The conferencing server provides high performance through the Telephony API – a programming interface for efficient multicasting • Chat services • Includes a chat service based on the Internet Relay Chat (IRC) protocol • Instant Messaging • Newsgroups • Requires the Network News Transport Protocol (NNTP) for newsgroups Email Services

19. Post Office Protocol (POP) • Created to allow for network-based access to mail stores • Many early Windows-based mail clients used POP for access to Internet mail • It allowed users to access UNIX-based mail servers • It was the dominant type of mail server on the Internet before the rise of the Microsoft Exchange in the 1990s • POP allows a central mail server to be managed to remain online at all times to receive mail for all its users • Received mail is queued on the server until a user connects via POP and downloads the queued mail • The user sends an e-mail through the mail server via SMTP Email Services

20. Internet Message Access Protocol (IMAP) • Created to support some limitations of POP • Keeping cached copies of user’s mails on the client, etc • Created to support mail access in three modes: • Online • Offline • Disconnected Email Services

21. POP and IMAP Basics • POP and IMAP each need a server process to handle requests • The server processes listen to ports 110 (POP) and 143 (IMAP) • Each request to and from the server is in clear-text ASCII Email Services

22. Common POP Commands Email Services

23. Understanding POP3 • More simplistic than IMAP4 • First step is to log on with user name and password • Can be used to: • List mail • Read mail • Download mail • Delete mail Email Services

24. Common IMAP Commands Email Services

25. Understanding IMAP4/UW-IMAP • The University of Washington’s IMAP4 and UW-IMAP implement both POP and IMAP protocols • Its features include the following: • Messages remain on server • Requires much more space on server • To keep track of the status of messages, flags are used • \Recent • \Seen • \Answered • \Flagged • \Deleted • \Draft Email Services

26. Installing the IMAP4/UW-IMAP and POP3 Server in Linux • To install the uw-imap server (by the University of Washington): • yum –y install uw-imap • Once installed, you have to enable the daemons by either: • Editing their configuration files such as /etc/xinetd.d/imap • Change disable=yes to disable=no • Using chkconfig • chkconfigimap on • chkconfig ipop3 on • Restart/start the xinetd to recognize the changes • service xinetd restart • service xinetd start Email Services

27. Other Mail Service Issues • Other issues with mail services include: • SSL Security • Availability • Log Files Email Services

28. E-mail Clients • Some e-mail clients include: • Elm (Linux) • Alpine (Windows, Linux) • Kmail (Windows, Linux) • Mutt (Windows, Linux) • Novell Evolution (Windows, Linux) Email Services

29. Configuring E-mail Clients • Typical information required for configuring e-mail clients include: • SMTP server IP address – outgoing server address • Your e-mail address • Your e-mail password • POP or IMAP server IP address – the incoming server address • the Exchange server and the University of Washington’s IMAP4 and UW-IMAP servers implement both protocols Email Services