stunnel version 3 has been removed from Debian. This is a dummy package to ease upgrading to stunnel4. . You may safely remove this package after the upgrade.
stunnel4 | Universal SSL tunnel for network daemons | Mehr ...
The stunnel program is designed to work as SSL encryption wrapper between remote client and local (inetd-startable) or remote server. The concept is that having non-SSL aware daemons running on your system you can easily setup them to communicate with clients over 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 programs' code. . This package contains a wrapper script for compatibility with stunnel 3.x
