Stunnel

Stunnel is a versatile SSL encryption wrapper that seamlessly adds SSL/TLS security to various inetd daemons and standalone servers, including POP2, POP3, IMAP, NNTP, SMTP, and HTTP. Built on the robust OpenSSL library, it supports all cryptographic algorithms available in OpenSSL. The tool is cross-platform and can leverage the FIPS 140-2 validated OpenSSL FIPS Provider when built according to security policies, with the latest Windows installer including this provider for enhanced compliance and security.