I believe you're looking at the wrong tool; consider using SSH rather than SSL. Using port forwarding, you should be able to arrange things so that the only unencrypted connections are to the loopbacks on both ends. There's even a Secure POP via SSH mini-HOWTO to step you through the process.

As for Perl modules, you have a choice... but I'll leave it to btrott to tell you why his Net::SSH::Perl modules are better than Net::SSH. :-)

If you have the skill to do so, consider writing the POP via SSH part of your program as a separate module, and sharing it. It will win you praise, and, if you choose to join the monastery, votes.