Using a email module like NET::SMTP or your example above can provide a more secure solution for you.
If you primary concern is to prevent spam:
Don't have an smtp server running unless your are hosting your own and know what you're doing.
Hard code the email addresses (to address and from address) in your script rather than allowing user controlled inputs. This way, even if someone does abuse the script, they won't be able to specify where the email is going.
Make sure that the only interface to your mailer is a web page. Worst case, if some script kiddie is spamming your box with mail, you have the weblogs and can have his isp to turn off the account.
