This guide covers mail server Ubuntu step by step, with every setting in the order you will use it. Postfix is the standard mail server on Linux: fast, secure by default, and the reason most of the internet’s mail runs on it. In a lab it teaches the fundamentals of SMTP, and in production it can both send and receive real mail. This guide installs it on Ubuntu Server.
dns LAB TOPOLOGY & PREREQUISITES
# example values used while writing and testing this guide
LAB VM
UBUNTU BUILD
VALIDATION
01constructionMail server Ubuntu: Step 1: Install Postfix
Update packages and install; the installer asks for the mail configuration type:
sudo apt update && sudo apt install postfix -y
Choose Internet Site (sends and receives directly) for a lab, and set the system mail name — your domain, for example lab.local. Skip the wizard options and you can always rerun it later with sudo dpkg-reconfigure postfix.
02downloadStep 2: Understand the Main Settings
Postfix’s configuration lives in /etc/postfix. The key values in main.cf:
myhostname— this server’s name, likemail.lab.localmydomainandmyorigin— the domain used on outgoing mailmydestination— domains this server accepts mail for locallymynetworks— hosts allowed to relay through this server; keep it to your lab subnetinet_interfaces— which network interfaces it listens on
After any edit, validate and reload: sudo postfix check && sudo systemctl reload postfix. In short, mail server Ubuntu works best when you follow the order above and verify each step.
03usbStep 3: Test Sending Mail
Install a mail utility and send a test:
sudo apt install mailutils -y
echo "Test body" | mail -s "Lab test" user@lab.local
Read the local delivery with the mail command, and watch the log at /var/log/mail.log — every SMTP conversation is logged there, which makes it the best debugging tool you have.
04terminalStep 4: Real-World Notes
Receiving mail from the internet needs port 25 open, a static IP, correct MX records in DNS (see the Ubuntu DNS guide) and matching reverse DNS. Most ISPs block residential port 25, so labs usually pair Postfix with a smart host for outbound delivery. For full mailbox service add Dovecot (IMAP/POP3). Compare with the Windows Server SMTP setup. In short, mail server Ubuntu works best when you follow the order above and verify each step.
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Finish this lab, then continue down the track. Each guide builds on the one before it.