[jay.scot]
[openbsd]
cat > /etc/mail/smtpd.conf << EOF
table aliases file:/etc/mail/aliases
table secrets file:/etc/mail/secrets
listen on lo0
action "local" mbox alias <aliases>
action "relay" relay host smtp+tls://mailrelay@server:port auth <secrets>
match for local action "local"
match for any action "relay"
EOF
chmod 640 /etc/mail/secrets
chown root:_smtpd /etc/mail/secrets
echo "mailrelay username:password" > /etc/mail/secrets