What are we doing?
- Configuring Postfix to use Google Mail as an SMTP relay
Running a send only SMTP server is useful for automating password recovery, account signup etc, but keeping mail out of the end user’s spam box is hard work. Relaying through Google means that the end user’s mail account will see the mail as having come from a Google relay rather than a SOHO IP address and will be much more likely to accept it.
This guide assumes you have a Google Mail account with appropriate permissions and have at least a Postfix SMTP server configured. Follow the guide here to setup Postfix.
Edit the Postfix configuration file
sudo nano /etc/postfix/main.cf
Add following lines-
relayhost = [smtp-relay.gmail.com]:587 smtp_use_tls=yes smtp_sasl_auth_enable = yes smtp_sasl_password_maps = hash:/etc/postfix/sasl_passwd smtp_tls_CAfile = /etc/ssl/certs/ca-certificates.crt smtp_sasl_security_options =
Create a file to store the Gmail username and password
sudo nano /etc/postfix/sasl_passwd
Add the following line
Create a db hash of the password file
sudo postmap /etc/postfix/sasl_passwd
Reduce permissions to the bare minimum on the password hash and remove the non-hash file
sudo chown postfix:postfix sasl_passwd.db
sudo chmod 400 sasl_passwd.db
sudo rm sasl_passwd
Force changes to take effect
sudo service postfix reload