Getting Started with Postfix: Install and Configure an MTA on Ubuntu

Published on January 10, 2026

Postfix MTA Ubuntu SMTP

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Postfix is the most widely deployed Mail Transfer Agent (MTA) on the internet. It handles sending and routing email between servers, and it’s the backbone of most self-hosted mail setups. This guide walks you through installing and configuring Postfix on Ubuntu 22.04.

Prerequisites

A VPS or dedicated server running Ubuntu 22.04
A public IP address (not blacklisted)
A domain name with DNS access
Root or sudo access

Step 1: Install Postfix

Update the package list and install Postfix:

sudo apt update
sudo apt install postfix -y

During installation, you’ll see a configuration dialog. Select Internet Site and enter your fully qualified domain name (FQDN), for example mail.example.com.

Verify the installation:

postconf mail_version

Step 2: Configure the Main Settings

The main Postfix configuration file is /etc/postfix/main.cf. Open it:

sudo nano /etc/postfix/main.cf

Set the following core parameters:

# Hostname and domain
myhostname = mail.example.com
mydomain = example.com
myorigin = $mydomain

# Network interfaces to listen on
inet_interfaces = all
inet_protocols = ipv4

# Trusted networks (localhost + your own IP)
mynetworks = 127.0.0.0/8

# Where to deliver local mail
home_mailbox = Maildir/

# Relay restrictions
smtpd_relay_restrictions =
    permit_mynetworks,
    permit_sasl_authenticated,
    reject_unauth_destination

After editing, reload Postfix:

sudo systemctl reload postfix

Step 3: Configure DNS Records

For your mail server to be reachable and trustworthy, set up these DNS records:

MX record — tells other servers where to deliver email for your domain:

example.com.  IN  MX  10  mail.example.com.

A record — resolves your mail server hostname:

mail.example.com.  IN  A  YOUR_SERVER_IP

PTR record (reverse DNS) — configure this through your VPS provider’s control panel. The PTR for YOUR_SERVER_IP should point to mail.example.com. This is critical for spam prevention.

Step 4: Enable TLS Encryption

Generate a self-signed certificate (or use Let’s Encrypt — recommended):

sudo apt install certbot -y
sudo certbot certonly --standalone -d mail.example.com

Add TLS settings to /etc/postfix/main.cf:

# TLS for incoming connections (smtpd)
smtpd_tls_cert_file = /etc/letsencrypt/live/mail.example.com/fullchain.pem
smtpd_tls_key_file  = /etc/letsencrypt/live/mail.example.com/privkey.pem
smtpd_tls_security_level = may
smtpd_tls_loglevel = 1

# TLS for outgoing connections (smtp)
smtp_tls_security_level = may
smtp_tls_loglevel = 1

Reload:

sudo systemctl reload postfix

Step 5: Send a Test Email

Use the mail command (from mailutils) to send a test:

sudo apt install mailutils -y
echo "Test body" | mail -s "Test Subject" you@gmail.com

Check the mail log:

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

Look for lines with status=sent to confirm successful delivery.

Step 6: Check Your IP Reputation

Before going live, verify your IP isn’t blacklisted. Use MXToolbox or check major RBLs:

host -t txt 1.0.0.127.zen.spamhaus.org

If your IP is listed, contact your VPS provider or request delisting.

Common Issues

“Connection refused” on port 25 — Many VPS providers block outbound port 25 by default. Contact support to request it be unblocked, or use port 587 (submission) for authenticated sending.

Emails going to spam — You likely need SPF, DKIM, and DMARC records. See our email authentication guide.

Postfix not starting — Check syntax errors: sudo postfix check and review /var/log/mail.err.

Next Steps

Postfix alone only handles SMTP (sending/relaying). To let users receive and read email via IMAP or POP3, you need to pair it with an IMAP server like Dovecot. See Setting Up Dovecot for the next step.