If you want to implement a captcha here is an easy I help put together http://www.websitecodetutorials.com/code/php/simple-php-captcha.php
If you want to do a honeypot here is a simple one http://www.websitecodetutorials.com/code/php/simple-php-honeypot.php
Otherwise you have the obfuscated email way or Fegal has a script that will watch the amount of time to fill out the form. If its done in a robot amount of time like 2 seconds the form is stopped.
But if the form is sending an email to a single destination address that is added after the form is submitted then the headers are constructed entirely on the server with no field in the form having any access. Therefore form hijacking is irrelevant in this situation. No fields would exist within the form that could be used to carry out hijacking.
Huh. So how would he/you know if the spambot is sending a spam message just to him or him and 100 others? I’m not being fesseciuos I really don’t know.