Postfix relaying emails with GMAIL SMTP (Centos 5.3)

I was tired of maintaining my email server so I decide to move everything to Google app. They can host your mail server up to 50 accounts for free, isnt it great?. So I have moved all my domains to Google apps and everything was working perfect, however I missed an issue RELAY emails!!

So I relaxed and I figured out how to relay emails using an Google app (GMAIL) account.

After reading a lot of post, I realized that everybody was missing a part of the problem.

Some people shows you how to create client certificates for postfix when you do not need them.

Some people tell you to get the root CA certificates when you already have them.

However the most important part is to have all the required packages to make it work.

For Centos 5.3

Verify package installed

# rpm -qa |grep postfix

postfix-2.3.3-2.1.el5_2

# rpm -qa |grep sasl

cyrus-sasl-lib-2.1.22-5.el5

cyrus-sasl-2.1.22-5.el5

cyrus-sasl-plain-2.1.22-5.el5

# rpm -qa |grep openssl

openssl-perl-0.9.8e-12.el5_4.1

openssl-devel-0.9.8e-12.el5_4.1

xmlsec1-openssl-1.2.9-8.1.1

openssl-0.9.8e-12.el5_4.1

openssl097a-0.9.7a-9.el5_2.1

Copy root CA certificates. Postfix needs to know the location of root CA.

# cp /etc/pki/tls/certs/ca-bundle.crt /etc/postfix/cacert.pem

Create file that stores GMAIL user and password.

# vi /etc/postfix/sasl_passwd

smtp.gmail.com user@domain:password

#postmap /etc/postfix/sasl_passwd

Edit /etc/postfix/main.cf

# Relay all e-mail via GMail.

relayhost = [smtp.gmail.com]:587

# SASL authentication

smtp_sasl_auth_enable=yes

smtp_sasl_password_maps = hash:/etc/postfix/sasl_passwd

smtp_sasl_security_options =

smtp_sasl_tls_security_options = noanonymous

smtp_sasl_mechanism_filter = login

# TLS

smtp_tls_eccert_file =

smtp_tls_eckey_file =

smtp_use_tls = yes

smtp_enforce_tls = no

smtp_tls_CAfile = /etc/postfix/cacert.pem

smtpd_tls_received_header = yes

tls_random_source = dev:/dev/urandom

Finally, restart postfix.

Enjoy it ...