How to Install and Configure Postfix on Ubuntu 22.04

In this guide we’ll look at how you can configure Postfix MTA as a send-only SMTP server on Ubuntu 22.04, meaning it doesn’t receive and process emails. Its job is only to act as a Local mail transfer agent. Postfix is a popular open-source Mail Transfer Agent (MTA) used in Linux and Unix environments.

A send-only mail server is useful especially when used in scripting, e.g. having a cron job that sends an email about the status of its execution, or an application that sends an email to you when certain events happen.

Configure Postfix as a Send-Only SMTP Server on Ubuntu

Installing and configuring Postfix as a Send-Only SMTP Server on Ubuntu is an easy process. Start by updating your system:

apt update

Also, set a hostname for the server so that emails will show a from address with a valid domain section.

hostnamectl set-hostname greencloud.example.com

Download mailutils which installs Postfix and other mail utils for you:

apt install mailutils

As the package installs, you’ll be asked to select an option on screen for your mail server. For ” General type of email configuration” window, select Internet site and click OK button

The next page will ask you to set your Mail server name, this can be a domain or server hostname with an A record.

Select OK to save the settings and finish the installation.

Configure Postfix MTA Server

Edit the Postfix configuration file /etc/postfix/main.cf to ensure it is configured as send-only ( Only relaying emails from the local server).

Set Postfix to listen on the 127.0.0.1loopback interface. The default setting is to listen on all interfaces.

inet_interfaces = loopback-only

Also, set myhostname to your Server FQDN

myhostname=myserver.example.com

See screenshot below

Restart the Postfix service for it to pick the new changes:

systemctl restart postfix

You have successfully installed and configured Postfix as a Send-only MTA server. To test email delivery, use the mail command like below

echo "Postfix Send-Only Server" | mail -s "Postfix Testing" [email protected]

You can also load existing data to mail

mail -s "Mail Subject" [email protected] < /root/green1/file.txt

This will send an email with the content loaded from /home/jmutai/file.txt
in the message section.