Mail Server Setup using Sendmail

on CentOS 5.8

Jeong Chul

tland12.wordpress.com

Computer Science

ITC and RUPP in Cambodia

Mail Server Setup using Sendmail

on CentOS 5.8 Part 1 • Step 1 Email Service

• Step 2 Essential Email Operation

• Step 3 Package installation and Startup

• Step 4 Sendmail Configuration – 1, 2

Part 2 • Step 5 Inbound Sendmail Aliases

• Step 6 Sendmail.cf file

• Step 7 Sendmail Operation

• Step 8 IMAP and POP3 on Dovecot

• Step 9 MUA Configuration

Mail Server Testing Environment

1.sever.chul.com: 192.168.80.25

Sendmail Mail server (mail.chul.com)

Evolution for MUA

2.client.chul.com: 192.168.80.10

Linux mail client

Thunderbird for MUA

3.Windows 7 : 192.168.80.1

Windows mail client

Outlook 2010 for MUA

Step 1 Email Service E-mail System Components

1.Mail User Agent (MUA):

A client used to compose and read e-mail (Outlook, Evolution, Thunderbird,

Mutt)

2.Mail Transfer Agent (MTA):

An SMTP server used to relay or accept e-mail for delivery (Postfix, Sendmail,

Exim, Qmail, Exchange server)

3.Mail Delivery Agent (MDA):

A program used by the final MTA to deliver e-mail to the message store

May be included with the MTA or a separate program such as procmail

4.Mail Access Agent (MAA):

An IMAP/POP3 server used by an MUA to access the message store (Dovecot,

Cyrus IMAP)

Step 2 Essential Email Operation

Step 3 Installation and startup

1.Package installation sendmail-cf-8.13.8-8.1.el5_7 sendmail-doc-8.13.8-8.1.el5_7 sendmail-8.13.8-8.1.el5_7 sendmail-devel-8.13.8-8.1.el5_7

2. Service startup and main directory # service sendmail start # ls –l /etc/mail/ 3. Service startup checking # ps –ef | grep sendmail # netstat –nat | grep 25 4. Runlevel registration # chkconfig sendmail on # chkconfig –list sendmail 5. Testing on command # telnet localhost 25 # mail –v –s ‘title’ linux@chul.com < /etc/passwd

Step 4 Sendmail Configuration (1)

1.Introduction to Sendmail Configuration /etc/mail/sendmail.mc and /etc/mail/sendmail.cf # m4 /etc/mail/sendmail.mc > /etc/mail/sendmail.cf "dnl " at the start of a line is a comment in /etc/mail/sendmail.mc

2. # service sendmail restart automatically builds configuration files Converts /etc/mail/sendmail.mc into /etc/mail/sendmail.cf

3. Incoming Sendmail configuration /etc/mail/sendmail.mc dnl dnl DAEMON_OPTIONS(`Port=smtp,Addr=127.0.0.1, Name=MTA')dnl /etc/mail/local-host-names ① mail.chul.com ② chul.com ③ jeong.net

Add a line for each domain/host for which we accept local delivery

Step 4 Sendmail Configuration (2)

4. Outgoing Sendmail configuration To relay e-mail sent by hosts on your internal network dnl DAEMON_OPTIONS(`Port=smtp,Addr=127.0.0.1, Name=MTA') dnl /etc/mail/access : each internal network or host for which the server will relay Connect:192.168.80 RELAY Connect:127.0.0.1 RELAY Connect: chul.com RELAY Connect: spam.net REJECT To: root@jeong.com ERROR:550 bad name From: spam@example.com REJECT

5. Sendmail: Masquerading in /etc/mail/sendmail.mc EXPOSED_USER(`root')dnl MASQUERADE_AS(`chul.com')dnl FEATURE(masquerade_envelope)dnl FEATURE(masquerade_entire_domain)dnl MASQUERADE_DOMAIN(chul.com)dnl

# service sendmail restart

Step 5 Inbound Sendmail Aliases

1.Local aliases: /etc/aliases ◄ Local mail forwarding fakename: realname

root: tland,linux,song,park,jeong

staff: :include /home/staff/staff_list ◄Mailing List

2. Virtual aliases: /etc/mail/virtusertable

admin@example.com user1

admin@chul.com user2

pack@itjeong.com jeong@example.com

@abc.com abc@aol.com

@dom1.org %1@dom2.org //same user different

domain

Step 6 Sendmail.cf file 1. Name for error message DnMAILER-DAEMON //if want, change

2. Version Number for security DZ8.13.8 O SmtpGreetingMessage=$j Sendmail $v/$Z; $b // j: hostname v&Z: version b: timestamp

3. Max Message Size (byte) O MaxMessageSize=2048000 //2 Mb

4. Max hop Count O MaxHopCount=17 // Max mail server for routing

5. Queue directory for sending and receiving temporarily O QueueDirectory=/var/spool/mqueue

6. Minimum time in queue before retry O MinQueueAge=30m

Step 7 Sendmail Operation

1./etc/mail/local-host-names must contain server's name and aliases

2.# mail -v user view SMTP exchange with local relay

3.# mailq and mailq -Ac view messages queued for future delivery

4.# sendmail –q reprocess the email queue

5.# tail -f /var/log/maillog view log in real-time

Step 8 IMAP and POP3 on Dovecot

1.Dovecot supports POP3, POP3s, IMAP, andIMAPs 2. Installation and startup # yum install dovecot # vi /etc/dovecot.conf protocols = imap imaps pop3 pop3s # service dovecot start 3.Service startup checking # ps –ef | grep dovecot # netstat –nat | grep 110,143 4. Runlevel registration # chkconfig dovecot on # chkconfig –list dovecot 5. Testing on command # telnet localhost 110 //pop3 # telnet localhost 143 //imap

Step 9 MUA Configuration

1.Graphical:

Evolution on Sever system

# yum install evolution

Thunderbird on Client system of Linux

# yum install thunderbird

Outlook 2010 on Client system of Windows 7

2.Text-mode: Mutt and Fetchmail mutt -f pop://user@server

mutt -f pops://user@server

Assignment

1.How to setup Postfix

2.How to setup qmail

3.How to setup Exim

4.Email server security

Mail Server Setup using Sendmail

on CentOS 5.8

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