Mail Relay Configure with postfix service

CONFIGURE MAIL RELAY IN POSTFIX MAIL SERVICE
note: postfix basic configuration was prerequisites.
 
Add below line to the /etc/postfix/main.cf file
relayhost = [smtp.gamil.com]:587
smtp_sasl_password_maps = hash:/etc/postfix/relay_password
smtp_sasl_security_options = noanonymous
smtp_cname_overrides_servername = yes
smtp_tls_security_level = may
smtp_tls_CAfile = /etc/postfix/cacert.pem
smtp_sasl_auth_enable = yes
sender_dependent_relayhost_maps = hash:/etc/postfix/relay_maps
smtp_sender_dependent_authentication = yes
address_verify_sender_dependent_relayhost_maps = $sender_dependent_relayhost_maps

# add new parameter for trusted relationship
smtp_generic_maps = hash:/etc/postfix/generic
Create cacert.pem just copy form /usr/she

[root@server ~]# cat /usr/share/purple/ca-certs/Equifax_Secure_CA.pem >> /etc/postfix/cacert.pem
[root@server ~]# cat /usr/share/purple/ca-certs/Thawte_Premium_Server_CA.pem >> /etc/postfix/cacert.pem
Create generic map file

[root@server ~]# cp generic generic.orig
[root@server ~]# vim generic
[root@server ~]# postmap generic
Create file /etc/postfix/relay_password and make db via postmap command.

[root@server ~]# vim /etc/postfix/relay_password
[root@server ~]# cat /etc/postfix/relay_password
user1@zmailtech.com gmailuser1@gmail.com:password1
user2@zmailtech.com gmailuser2@gmail.com:password2
[root@server ~]#

[root@server ~]# postmap /etc/postfix/relay_password
Create file /etc/postfix/relay_maps and make db via postmap command.

[root@server ~]# vim /etc/postfix/relay_maps
[root@server ~]# cat /etc/postfix/relay_maps
@gmail.com [smtp.gmail.com]:587
[root@server ~]# postmap /etc/postfix/relay_maps
service postfix restart

[root@server ~]# service postfix restart
Shutting down postfix                                 [ OK ]
Starting postfix:                                     [ OK ]
[root@server `]#