Install / Configure a Relay-only mail host on ec2

Install postfix

apt-get install postfix mailutils

stop the service

/etc/init.d/postfix stop

Edit /etc/postfix/master.cf and change

smtp      inet  n       -       -       -       -       smtpd

to

#smtp      inet  n       -       -       -       -       smtpd

Edit /etc/postfix/main.cf and change

myhostname = ip-10-127-126-193.ec2.internal
alias_maps = hash:/etc/aliases
alias_database = hash:/etc/aliases
myorigin = /etc/mailname
mydestination = mysub.mydom.com, ip-10-127-126-193.ec2.internal, localhost.ec2.internal, localhost
relayhost =
mynetworks = 127.0.0.0/8 [::ffff:127.0.0.0]/104 [::1]/128
mailbox_size_limit = 0
recipient_delimiter = +
inet_interfaces = all

to

myhostname = mysub.mydom.com
alias_maps = hash:/etc/aliases
alias_database = hash:/etc/aliases
myorigin = /etc/mailname
mydestination = mysub.mydom.com, localhost.mydom.com, ip-10-127-126-193.ec2.internal, localhost.ec2.internal, localhost
relayhost = mydom.com
mynetworks = 127.0.0.0/8 [::ffff:127.0.0.0]/104 [::1]/128
mailbox_size_limit = 0
recipient_delimiter = +
inet_interfaces = all
local_transport = error:local delivery disabled

Restart postfix

/etc/init.d/postfix restart

test with mail

root@ip-10-127-126-193:/etc/postfix# mail dixon@mydom.com
Cc: 
Subject: Mims testing from root@mysub.mydom.com to dixon@mydom.com 201012120753
.
.
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