Install
# OpenBSD – built-in:
rcctl enable smtpd && rcctl start smtpd
# Other platforms:
# Ubuntu/Debian:
apt install opensmtpd
# AlmaLinux/RHEL:
dnf install opensmtpd
# Arch:
pacman -S opensmtpd
Basic /etc/mail/smtpd.conf
pki mail.example.com cert "/etc/ssl/mail.example.com.crt"
pki mail.example.com key "/etc/ssl/private/mail.example.com.key"
table aliases file:/etc/mail/aliases
listen on all tls pki mail.example.com
listen on all port submission tls-require pki mail.example.com auth
action "local" mbox alias <aliases>
action "relay" relay
match for local action "local"
match from local for any action "relay"
Check and restart
smtpd -n
rcctl restart smtpd 2>/dev/null || systemctl restart opensmtpd
Send a test
echo "Subject: test" | sendmail [email protected]
