Stunnel is a free SSL proxy server that provides SSL services to Windows programs. Stunnel is easy to install, very robust, and functions transparently with very little overhead.
Stunnel is required by SEE application programs when connecting to an email server that requires SSL services such as Gmail, Hotmail, and Yahoo.
You must use (with SEE) the stunnel.pem file created when Stunnel version 5.42 (or above) was installed, not an older version of stunnel.pem.
Stunnel can be configured and controlled automatically (without any user intervention) if you are using SEE version 7.0 (or above). See http://www.marshallsoft.com/stunnel_auto.htm