look for "/etc/tcp.smtp" in that document.
The first think you should do as a responsible sysadmin is:
svc -d /service/qmail-*
Then figure out how to stop the open relay. However, probably most of the email messages are going to go to bad addresses, so your queue will be full of bad messages and qmail will continue to attempt deliver for about a week. If you don't have a bunch of email in your queue, you should consider figuring out how to delete all the messages in your queue before starting qmail again.