Setting up postfix to use Gmail SMTP under Ubuntu
If you want to use a gmail account as a free SMTP server on your Ubuntu server, you will find this article useful. This guide is tested with Ubuntu 12.04 (updated for 15.10).
First, install all necessary packages:
# sudo apt-get install postfix mailutils libsasl2-2 ca-certificates libsasl2-modules
If this is the first time install of postfix, the configuration wizard will run on install and asks you a couple of questions. Simply select your server as
Internet Site and for FQDN use something like
mail.example.com. Replace with your domain
Open your postfix config file:
# vi /etc/postfix/main.cf
add the following lines to it:
relayhost = [smtp.gmail.com]:587 smtp_sasl_auth_enable = yes smtp_sasl_password_maps = hash:/etc/postfix/sasl_passwd smtp_sasl_security_options = noanonymous smtp_tls_CAfile = /etc/postfix/cacert.pem smtp_use_tls = yes
Open or create the sasl_passwd file to include your Gmail username and password:
# vi /etc/postfix/sasl_passwd
And add following line:
If you want to use your Google App's domain, please replace
@gmail.com with your
Fix permission and update postfix config to use sasl_passwd file:
# chmod 0400 /etc/postfix/sasl_passwd # postmap /etc/postfix/sasl_passwd
Next, validate certificates to avoid running into error. Just run following command:
For Ubuntu 12.04, use:
# cat /etc/ssl/certs/Thawte_Premium_Server_CA.pem | tee -a /etc/postfix/cacert.pem
For Ubuntu 14.04, 15.10, use:
# cat /etc/ssl/certs/thawte_Primary_Root_CA.pem | tee -a /etc/postfix/cacert.pem
Finally, reload postfix config for changes to take effect:
# /etc/init.d/postfix reload
Check if mails are sent via Gmail SMTP server
If you have configured everything correctly, following command should generate a test mail from your server to your mailbox.
# echo "Test mail from postfix" | mail -s "Test Postfix" firstname.lastname@example.org
To further verify, if mail sent from above command is actually sent via Gmail's SMTP server, you can log into Gmail account USERNAME@gmail.com with PASSWORD and check “Sent Mail” folder in that Gmail account. By default, Gmail always keeps a copy of mail being sent through its web-interface as well as SMTP server. This logging is one strong reason that we often use Gmail when mail delivery is critical.
Once configured, all emails from your server will be sent via Gmail.