couriertls(1) on Linux
The text d681afe2f52c, as Debian 9 (Stretch) shipped it.
the Courier mail server TLS/SSL protocol wrapper
Flags it lists
-
-host -
-localfd -
-port -
-printx509 -
-protocol -
-remotefd -
-server -
-statusfd -
-tcpd -
-verify