Postfix Postfix is a free and open-source mail transfer agent (MTA) that routes and delivers electronic mail. This is required in order to be able to send mails from the local machine (without using any vendor’s client) Installation sudo apt-get install postfix Postfix has be configured. The suggested way to do is via: sudo dpkg-reconfigure postfix. You can also directly edit /etc/postfix/main.cf file and make changes to the configuration. For most of the purposes dpkg-reconfigure should suffice.