Postfix is a popular, high-performance Mail Transfer Agent (MTA) that routes and delivers email. This guide installs and configures Postfix as an outgoing SMTP server on Ubuntu 24.04 LTS.

Tested and valid on:

  • Ubuntu 24.04 LTS

Prerequisites

  • Ubuntu 24.04 LTS server
  • A registered domain name
  • DNS MX records pointing to your server
  • A user with sudo privileges

Step 1 – Install Postfix

Install Postfix:

sudo apt update
sudo apt install postfix mailutils -y

In the setup dialog, select Internet Site and enter your domain name.

Step 2 – Configure Postfix

Edit the main configuration:

sudo nano /etc/postfix/main.cf

Key settings:

myhostname = mail.example.com
mydomain = example.com
myorigin = $mydomain
inet_interfaces = all
mydestination = $myhostname, $mydomain, localhost.$mydomain, localhost
relayhost =
mynetworks = 127.0.0.0/8 [::ffff:127.0.0.0]/104 [::1]/128

Step 3 – Restart Postfix

Apply changes:

sudo systemctl restart postfix
sudo systemctl enable postfix

Step 4 – Test Sending Email

Send a test email from the command line:

echo 'Test email from Ubuntu 24.04' | mail -s 'Postfix Test' [email protected]

Step 5 – Check the Mail Queue

View and manage the mail queue:

mailq
postqueue -f   # flush the queue

Step 6 – Configure TLS for SMTP

Enable TLS encryption in Postfix:

sudo nano /etc/postfix/main.cf

Add:

smtpd_tls_cert_file=/etc/ssl/certs/mysite.crt
smtpd_tls_key_file=/etc/ssl/private/mysite.key
smtpd_tls_security_level=may
smtp_tls_security_level=may

Restart:

sudo systemctl restart postfix

Step 7 – View Mail Logs

Monitor Postfix activity:

sudo tail -f /var/log/mail.log

Conclusion

Postfix is now running on Ubuntu 24.04 LTS. For a complete mail server, pair Postfix with Dovecot for IMAP access, SpamAssassin for spam filtering, and OpenDKIM for email authentication.