On Unix the standard way to do this is by running sendmail, mail, or Mail, and if you're on Unix that's what I would do to keep things simple. If you need to run on a non-Unix platform, probably using an existing SMTP module (like Email::Send::SMTP) is your best bet; that will work on any platform.

It's generally not that hard to install other libraries along with your script. A useful tool for bundling your script and all of the modules it uses into one executable is PAR.

Update: Fix typo in module name.