starttls-program is a variable defined in `starttls.el'.
Its value is
"starttls"
This variable may be risky if used as a file-local variable.
Documentation:
The program to run in a subprocess to open an TLSv1 connection.
This program is used when the `starttls' command is used,
i.e. when `starttls-use-gnutls' is nil.
You can customize this variable.