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.