The stunnel program is designed to work as an SSL encryption wrapper
between a remote client and a local (inetd-startable) or remote server.
The concept is that despite having non-SSL aware daemons running on your
system, you can easily set them up to communicate with clients over
a secure SSL channel.

stunnel can be used to add SSL functionality to commonly used inetd
daemons like POP-2, POP-3 and IMAP servers without any changes in
the program code.