Postfix on AlmaLinux 9

Install packages

dnf install -y postfix s-nail swaks
systemctl enable --now postfix

Set identity

postconf -e "myhostname = mail.example.com"
postconf -e "mydomain = example.com"
postconf -e "myorigin = $mydomain"

Relay safety

Never make Postfix an open relay. Define trusted networks narrowly and require authentication for remote submission.

postconf -e "mynetworks = 127.0.0.0/8, [::1]/128"
postconf -e "smtpd_relay_restrictions = permit_mynetworks, permit_sasl_authenticated, reject_unauth_destination"

Validate and reload

postfix check
postconf -n
systemctl reload postfix
ss -lntp | grep master

Test

swaks --server 127.0.0.1 --from [email protected] --to [email protected]

Logs

On AlmaLinux, inspect journald and the configured mail log destination. Confirm the actual logging path before relying on copied troubleshooting commands.

Production checklist

• Hostname and PTR aligned
• No open relay
• TLS configured
• Submission authenticated
• Queue monitored
• DKIM signing integrated
• Abuse and bounce processes documented