There are a huge number of spambots out there nowadays and they try and use your contact forms to send spam. If you've been slightly careful, the spam is not sent to its intended recipients, but you end up receiving it.
One way of stopping this is using a Captcha, an image with text which needs to be entered in your form.
Here follows a brief example;
File 1: contact.php
File 2: ocr_captcha.class.php
File 3: arial.ttf (you'll need to upload this to the same directory as the above files) You can find this file in your %WINDOWS%/fonts directory on your computer
Put both files in the same directory. Create a new directory "tmp" to hold temp images. Give httpd full permissions on the "tmp" directory
Make sure you enter your email address in the $email_to value.
contact_example.zip updated to correct filename typo