📦 Installation Command
apt install postfix postfix-pcre
Postfix SMTP Ports & Mail Server Configuration
postfix systemctl: postfixFast, secure Mail Transfer Agent (MTA). Sends and receives email via SMTP.
🔌 Default Ports
25
tcp
SMTP
465
tcp
SMTPS (implicit TLS)
587
tcp
Submission (STARTTLS)
⚙️ Configuration Files
/etc/postfix/main.cf/etc/postfix/master.cf/etc/mailname/etc/aliases
📂 Default Directories
- config:
/etc/postfix - data:
/var/spool/postfix - logs:
/var/log/mail.log - mailboxes:
/var/mail
🔐 Default Credentials
Username:N/A (system users)
Password:N/A (system auth)
💡 Uses system users or can integrate with virtual users via database/LDAP
📌 Dependencies
⚠️ Conflicts
✅ Works With
🛡️ Security Notes
Disable open relay, use TLS, configure SPF/DKIM/DMARC, set smtpd_recipient_restrictions, use fail2ban for brute force protection
❓ Frequently Asked Questions
What ports does Postfix use?
Postfix uses port 25 (SMTP), 465 (SMTPS), and 587 (submission) for mail.
Difference between port 25 and 587?
Port 25 is for server-to-server mail. Port 587 is for client submission with authentication.
Where is Postfix config?
Main config at /etc/postfix/main.cf, additional settings in master.cf.