106215 PHP mail form

We need a php mail form to use for all of our sites. Our current form is being used by spammers. Requirements, Only will accept data from our website. Does not display email to teh robots. Does not allow for auto injection of text by robots. This must be a spam free script. We will need to be able to change the to to to addresss in the actual script and set the redirect thank you page and the subject. This form will be used for basic contact forms. example [login to view URL] must be php form. We will upload this same script on multiple sites. We have no problem existing form but must be spam proof!