A TLS-encrypted SMTP service so your users can send mail through your server without passing clear-text passwords across the network.
Set up the service directory, download John Simpson's SMTP run script, and set it's permissions:
cd /var/servicemkdir -m 1755 smtp-tlscd smtp-tlswget http://qmail.jms1.net/scripts/service-qmail-smtpd-run mv service-qmail-smtpd-run runchmod 700 run
/var/service/smtp-tls/run
IP= PORT=587 SSL=0