Currently, this has only been tested with sendmail. Edit and compile stls.c to suit your needs. Currently sendmail is being called and specifies a special configuration file that allows controlled relaying. Make sure files are in proper locations. Once you have it working, include smtps1 in your local firewalling so that it is not directly accessible from the outside world.
Contributors are welcome.
Installing some limits on the resources used by these programs. More flexible SMTP conversation with stls.c. More generalization of listen-stls to support more SMTP servers.