foreach( $_POST as $value ){
  if( stripos($value,'Content-Type:') !== FALSE ){
    mail('[email protected]','Spammer Bot Attempt',$_SERVER['REMOTE_ADDR']);
     exit("{$_SERVER['REMOTE_ADDR']} Has been Recorded");
  }
}

http://www.nyphp.org/PHundamentals/8_Preventing-Email-Header-Injection

Stop a spam email form header injection attack - ie stop spammers from hijacking a web form to send junk mail

Anti spam web email  form

email

PHP