1. SMTP/POSTFIX

2. MTA – Mail Transfer Agent MDA – Mail Delivery Agent
MUA – Mail User Agent
MRA – Mail Retrieval Agent
MAA- Mail Access Agent
Internet
DNS
Chk MX Record
MTA
<XYZ.com>
MDA
MTA
<ABC.com>
MRA/MAA
POP3/IMAP
/var/spool/mail
MUA
(Ex: Outlook)
MUA
(Ex: Outlook)

3. Steps: TCP port used by postfix – TCP 25 Yum remove <sendmail>
Package Name – Postfix
Script file - /etc/init.d/postfix
/etc/init.d/postfix <start>
/etc/init.d/postfix <stop>
/etc/init.d/postfix <restart>
/etc/init.d/postfix <status> Or
Service postfix <start> <stop> <restart>
Chkconfig postfix on (for run-level 3,5)
Configuratin File
/etc/postfix/master.cf
/etc/postfix/main.cf
To install
Yum install –y <postfix>

4. Update configuration file:
Vi /etc/postfix/main.cf
## Line no 75 - Uncomment and set your mail server FQDN ##
myhostname = server.unixmen.local
## Line 83 - Uncomment and Set domain name ##
mydomain = unixmen.local
## Line 99 - Uncomment ##
myorigin = $mydomain
## Line Set ipv4 ##
inet_interfaces = all
## Line Change to all ##
inet_protocols = all
## Line Comment ##
#mydestination = $myhostname, localhost.$mydomain, localhost,
## Line Uncomment ##\
mydestination = $myhostname, localhost.$mydomain, localhost, $mydomain
## Line Uncomment and add IP range ##
mynetworks = /24, /8
## Line Uncomment ##
home_mailbox = Maildir/
And…
Restart the postfix mail service
/etc/init.d/postfix restart

5. Test the mail: Create new user ID – student
useradd –d /home/student –c “student ID” –m student
As a root user, send test to student ID <student>
$ su – root #

6. Login as a <student> & check the mail:

7. Send mail with Attachment: (MUTT)
Yum install -y <mutt>
mail -s "test mail with attachment" < /home/user1/atachment.txt
To send mail with attachment:
# mutt mail

8. To read the mail with attachment
Login as student, they type <mutt>

9. Configure to send emails to relay server:
# vi /etc/postfix/main.cf